Ch. 17 - Chemical ThermodynamicsWorksheetSee all chapters
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Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
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Ch.10 - Molecular Shapes & Valence Bond Theory
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Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Entropy is the disorder or chaos associated with a system’s inability to convert thermal energy into mechanical work. 

Entropy and Spontaneity

Concept #1: The 2nd and 3rd Laws of Thermodynamics

The 2nd Law of Thermodynamics states systems (chemical reactions) spontaneously move to state of disorder. 

Concept #2: Entropy & Phase Changes

During a phase change as our molecules grow farther apart then entropy will increase. 

During a phase change as our molecules grow closer together then entropy will decrease.

Example #1: Which should have the highest molar entropy at 25oC?

Example #2: Which substance has greater molar entropy. 

Entropy and Phases

When comparing the entropy of different compounds then we must follow a set of guidelines in the following order. 

Example #3: Arrange the following substances in the order of increasing entropy at 25oC. 

Example #4: Containers A and B have two different gases that are allowed to enter Container C. Based on the image of Container C, what is the sign of entropy, ΔS°.

Practice: An ideal gas is allowed to expand at constant temperature. What are the signs of ∆H, ∆S & ∆G.

Whenever a phase change occurs, first determine if bonds are broken or formed to figure out the signs of enthalpy and entropy. Afterwards, determine if the reaction is spontaneous to determine the sign of Gibbs Free energy. 

Example #5: Consider the spontaneous fusion of ice at room temperature. For this process what are the signs for ΔH, ΔS and ΔG?

Practice: Consider the freezing of liquid water at 30°C. For this process what are the signs for ∆H, ∆S, and ∆G?

If bonds are broken then the entropy of a reaction increases, but if bonds are formed then the entropy of a reaction decreases. 

Practice: Predict the sign of ∆S in the system for each of the following processes:

a) Ag+ (aq) + Br - (aq) → AgBr (s)

b) CI2 (g) → 2 CI - (g)

c) CaCO3 (s) → CaO (s) + CO2 (g)

d) Pb (s) at 50°C → Pb (s) at 70°C

Practice: For each of the following reactions state the signs of ∆H (enthalpy) and ∆S (entropy):

a) Fusion of ice.

b) Sublimation of CO2

c) Vaporization of aqueous water.

d) Deposition of chlorine gas.

e) Condensation of water vapor. 


 Entropy and Calculations

The 2nd Law of Thermodynamics states that the entropy of the universe is always increasing and so it must always be greater than zero. 

Concept #3: The Universe & Entropy

The entropy of the universe takes the look at the entropy of our system (the chemical reaction) and of the universe. 

Concept #4: Total Entropy & Spontaneity

If the entropy is greater than zero then we classify the process as spontaneous. 

Concept #5: The Entropy of a Reaction

The entropy, enthalpy and Gibbs Free energy of a reaction is equal to products minus reactants. 

Example #6: The oxidation of iron metal is given by the following reaction: 

Practice: Diethyl ether (C4H10O2, MW = 90.1 g/mol) has a boiling point of 35.6oC and heat of vaporization of 26.7 kJ/mol. What is the change in entropy (in kJ/K) when 3.2 g of diethyl ether at 35.6oC vaporizes at its boiling point?

Concept #6: Trouton's Rule & Boltzmann's Equation 

Additional Problems
Which of the following has the smallest molar entropy at 298 K? 1. Ne(g) 2. F2(g) 3. N2(g) 4. Cl2(g) 5. He2(g)
When an aqueous solution containing Al 3+ at 25°C is mixed with an aqueous solution of hydroxide at 25°C an immediate precipitate of insoluble aluminum hydroxide is formed: Al 3+ (aq) + 3 OH – (aq) →  Al(OH)3 (s) The standard reaction enthalpy (ΔH°) of this reaction is -61.33 kJ/mol. a) Calculate ΔS°, ΔSsurr and ΔStot for this reaction
Which of the following processes result(s) in an increase in the entropy of the system? All systems are closed systems.  
For the dissociation reaction of the acid HF HF ⇌ H+ + F - ΔS is observed to be negative. The BEST explanation for this is: A. This is the expected result since each HF molecule produces two ions when it dissociates. B. Hydration of the ions produces the negative value of ΔS. C. The reaction is expected to be exothermic and thus ΔS should be negative. D. The reaction is expected to be endothermic and thus ΔS should be negative. E. None of these can explain the negative value of ΔS.
Consider the reaction of N2O5 at 25°C for which the following data are relevant: 2 N2O5 (g) ⇌ 4 NO2 (g) + O2 (g) What is ΔS° for the reaction (in J/K)? A. 89.5 B. 249.2 C. 453.8 D. 249.2 E. -115.6 
One of the major sources of NOx compounds in our atmosphere is the reaction between nitrogen and oxygen, for example N2(g) + 2O2(g) → 2NO2(g) This reaction is not favored at normal surface temperatures, but it does occur within internal combustion engines when air is mixed with the fuel to provide oxygen for the combustion reaction.    a. Before doing any calculations, predict the sign of ΔS°. ___________________.  Explain your reasoning.   b. Now calculate ΔH° and ΔS° for the above reaction. Some thermodynamic data is provided in the table below.   c. Is there a temperature range at which the above reaction would be spontaneous? If so, give the temperature range. If not, speculate on why the reaction occurs at higher temperatures.      
Which of the following species has the highest entropy (S°) at 25°C? A. MgCO3(s) B. CO(g) C. H2O(l)  D. CO2(g) E. CH3OH(l)
Which one of the following reactions is most likely to have a positive ΔS°? a) Cu2+ (aq) + 4 Cl -  (aq) → CuCl42-(aq) b) SiH4 (g) + 2O2 (g) → SiO2 (s) + 2 H2O (g) c) SiF4 (g) + 2 H2O (g)  → SiO2 (s) + 4 HF (g) d) H2O (l)  → H2O (s) e) NO (g) + O3 (g)  → NO2 (g) + O2 (g)    
Which one of the following reactions is likely to have a ΔS° close to zero (in other words, neither positive nor negative)? a) PCl 3(g) + Cl2(g) ⇌ PCl 3(g) b) 2KClO 3(s) ⇌ 2KCl(s) + 3O 2(g) c) CO(g) + H 2O(g) ⇌ CO 2(g) + H 2(g) d) CO 2(g) ⇌ CO 2(s) e) C 5H 12(l) + 8O 2(g) ⇌ 5CO 2(g) + 6H 2O(g)     Place the following compounds in order of increasing S°: PCl5(s)          PCl 5(g)          PCl 3(g) a) PCl5(s) < PCl5(g) < PCl3(g) b) PCl5(s) < PCl3(g) < PCl5(g) c) PCl5(g) < PCl5(s) < PCl3(g) d) PCl5(g) < PCl3(g) < PCl5(s) e) PCl3(g) < PCl5(g) < PCl5(s) f) PCl3(g) < PCl5(s) < PCl5(g)      
Ce2(SO4)3 becomes less soluble in water as temperature increases because it has a negative entropy of solvation. Most other salts become more soluble in water with increasing temperature because their entropy of solvation is positive. Which explanation best describes this discrepancy? a) The bond strength of Ce2(SO4)3 is very strong, which leads to an increase in the order of the system during the reaction. b) The highly charged Ce3+ and SO42- ions become surrounded by a uniquely ordered sphere of water molecules, which increases the order of the system. c) The solid structure of Ce2(SO4)3 lacks a highly ordered crystal structure thereby leading to a decrease in the order of the system during the reaction.  d) The ions Ce3+ and SO42- repel water molecules, which leads to a decrease in the order of the system during the reaction. e) There is no explanation for this phenomenon. 
For which of these processes is the value of Δ S expected to be negative? I. Sugar is dissolved in water. II. Steam is condensed. III. CaCO3 is decomposed into CaO and CO2. a) I only b) I and III only c) II only d) II and III only
In which process is entropy decreased ? a) dissolving sugar in water b) expanding a gas c) evaporating a liquid d) freezing water
HI has a normal boiling point of -35.4°C, and its ΔHvap is 21.16kJ/mol. Calculate the molar entropy of vaporization (ΔSvap). A. 68.6 J/K • mol B. 0.068 J/K • mol C. 598 J/K • mol D. 89.0 J/K • mol E. 75.2 J/K • mol
The diagram below shows the variation in entropy with temperature for a substance that is a gas at the highest temperature depicted. Accordingly, which of the following statements is not true? (a) The “zero point” is explained by the Second Law of Thermodynamics. (b) The entropy of a substance increases with temperature. (c) A solid has the least dispersed energy and the lowest entropy. (d) The vertical line 1 corresponds to ΔSfusion. (e) The increase in entropy for liquid  ⇌ gas is greater than for solid ⇌ liquid  
For which reaction, carried out at standard conditions, would both the enthalpy and entropy changes drive the reaction in the same direction? a) 2 H2 (g) + O2 (g) → 2 H2O (l)         ΔH = - 571.1 kJ b) 2 Na (s) + Cl2 (g) → 2 NaCl (s)      ΔH = - 822.0 kJ c) N2 (g) + 2 O2 (g) → 2 NO2 (g)        ΔH = + 67.7 kJ d) 2 NH3 (g) → N2 (g) + 3 H2 (g)        ΔH = + 92.4 kJ
Which of the following has the greatest entropy, S? (a) 1.00 mole of liquid water at 30° C (b) 1.00 mole of water vapor at 30° C (c) 1.00 mole of regular ice at -10° C  (d) 1.00 mole of “dry ice” (solid CO2) at -10° C (e) 1.00 mole of water under 10 atm of pressure at -10° C
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 298 K.   N2(g) + 2 O2(g) → 2 NO2(g) ΔH = +66.4 kJ   a) ΔSsurr = +223 J/K b) ΔSsurr = -223 J/K c) ΔSsurr = -66.4 J/K d) ΔSsurr = +2656 kJ/K  
Which of these species has the highest entropy (S°) at 25°C? A) CH3OH(l) B) CO(g) C) MgCO3(s) D) H2O(l) E) Ni(s)
Which responses include all of the following processes that are acccompanied by an increase in entropy? 1. I2(s) → I2(g) 2. 2I(g) → I2(g) 3. 2NH3(g) → N2(g) + 3H2(g) 4. Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s)   A) 1, 2 B) 1, 3 C) 3, 4 D) 3 E) 2, 4  
Which of the following processes would have a positive ΔSsys value? (a) He(g), 2 atm → He(g), 10 atm (b) 2 NO2(g) → N2O4(g) (c) H2(g) + I2(s) → 2 HI(g) (d) 2 Ag(s) + Br2(l) → 2 AgBr(s) (e) O2(g) → O2(aq)
Determine ΔS° for the reaction SO3(g) + H2O(l) → H2SO4(l).                  S° (J/K•mol) SO3(g)         256.2 H2O(l)         69.9 H2SO4(l)     156.9   A) 169.2   J/K•mol B) 1343.2 J/K•mol C) -169.2  J/K•mol D) -29.4    J/K•mol E) 29.4     J/K•mol
Elemental boron can be forrmed by reaction of boron trichloride with hydrogen.  BCl3(g) + 1.5H2(g) → B(s) + 3HCl(g) Substance:    BCl3(g)       H2(g)          B(s)         HCl(g) (J/K•mol):          ?            130.6         5.87      186.8   If ΔS°rxn = 80.3 J/K, what is S° for BCl3(g)? A) -18.2   J/K•mol B) 18.2    J/K•mol C) 290.1  J/K•mol D) 355.4  J/K•mol E) 450.6  J/K•mol
Identify the change in state for which there is an increase in the entropy of the system. A) water condensing B) crystallization of NaCl(s); NaCl(aq) → NaCl(s) C) compression of Air; air(1atm) → air(200 atm) D) ddry ice subliming E) water freezing
Which of the following processes is accompanied by a decrease in entropy of the system? A) C6H12O6(s) → 3CH3OH(l) + CO(g) + 2C(s) B) Ni(s) + 4CO(g) → Ni(CO)4(g) C) NaHCO3(aq) + HCl(aq) → H2O(l) + NaCl(aq) + CO2(g) D) NaClO3(s) → Na+(aq) + ClO31-(aq) E) None of the above
Calculate the normal boiling point of chloroform given that the standard entropy and enthalpy of vaporization of chloroform is +93.7 J/K/mol and 31.4 kJ/mol, respectively. 1. 215 K 2. 450 K 3. 405 K 4. 375 K 5. 335 K
Place the following in order of increasing molar entropy at 298 K. [Least (left) - Most (right)]     C(s)           O2(g)         Ne (g) A) C(s)    <   O2(g)    <   Ne (g) B) O2(g)  <   C(s)      <  Ne (g) C) Ne(g)   <  O2(g)      <  C(s) D) Ne(g)    <  C(s)        <  O2(g) E) C(s)       <  Ne(g)     <  O2(g)
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 398 K. Predice whether or not this reaction will be spontaneous at this temperature. 2 N2(g) + O2(g) → 2 NO2(g)                   ΔH = +163.2 kJ A) ΔSsurr = -548 J/K, reaction is spontaneous B) ΔSsurr = -548 J/K, reaction is not spontaneous C) ΔSsurr = -410 J/K, reaction is not spontaneous D) ΔSsurr = -410 J/K, reaction is spontaneous E) ΔSsurr = -410 J/K, it is not possible to predict the spontaneity of this reaction without more information.
Calculate ΔS°rxn for the following rreaction. The S° for each species is shown below the reaction.                          H   2      +     Cl 2(g)   →   2HCl(g) S°(J/mol•K)     130.7         223.1         186.9 A) -20 J/K B) +20 J/K C) -166.9 J/K D) +166.9 J/K E) +466.2 J/K
Identify the change in state that  DOES NOT have an increase in entropy of the system. A) water evaporating B) water boiling C) ice melting D) dry ice subliming E) water freezing
In which example does entropy increase? I. A piece of fruit freezes in liquid nitrogen. II. Librarians put library books back onto shelves at the end of the day. III. Liquid nitrogen boils in a beaker at room temperature. IV. Dry ice sublimes. V. A balloon collapses as its contents cool in liquid nitrogen. 1. I, III, IV, or V only 2. IV or V only 3. I, II, III, IV, or V 4. II only 5. IV only 6. II or III only 7. III only 8. II or IV only 9. III or IV only
Which of the following processes shows a decrease in entropy of the system? A) CH3OH(l) → CO(g) + 2H2(g) B) COCl2(g) → CO(g) + Cl2(g) C) 2 NO(g) + O2(g) → 2 NO2(g) D) NaClO3(s) → Na+(aq) + ClO3-(aq) E) None of the above will show a decrease in entropy.  
Predict which substance in each pair has the greater molar entropy: a) butane, CH3CH2CH2CH3 or 2-butene, CH 3CH=CHCH3 b) Ne (g) or Xe (g) c) CH4 (g) or CCl4 (l) d) CH3OH (l) or C 2H5OH (l) e) KClO3 (s) or KClO3 (aq) f) Na (s) or K (s)
Which of the following would probably have a positive ∆S value? 1. O2(g) → O2(aq) 2. He(g, 2 atm) → He(g, 10 atm) 3. 2 NO2(g) → N2O4(g) 4. 2 Ag(s) + Br2(l) → 2 AgBr(s) 5. H2(g) + I2(s) → 2 HI(g)
Predict the sign of ΔS for each of the following: a) A piece of wax melting b) Silver chloride precipitating from solution c) Alcohol evaporating d) A solid explosive converting to a gas e) 2 K(s) + F2 g) → 2 KF(s) f) NH3(g) + HBr(g) → NH4Br(s) g) NaClO3(s) → Na+(aq) + ClO3- (aq)
Place the following in order of increasing molar entropy at 298 K. CO2          C 3H 8             SO A) CO2 < C3H8 < SO B) C3H8 < CO2 < SO C) CO2 < SO < C3H8 D) SO < C3H8 < CO2 E) SO < CO2 < C3H8
Consider the following reaction at constant P. Use the information here to determine the value of ΔSsurr at 398 K. Predict whether or not this reaction will be spontaneous at this temperature. 4 NH3(g) + 3 O2(g)  →  2 N2(g) + 6 H2O(g) ΔH = -1267 kJ A) ΔSsurr = +3.18 kJ/K, reaction is spontaneous B) ΔSsurr = -12.67 kJ/K, reaction is spontaneous C) ΔSsurr = +50.4 kJ/K, reaction is not spontaneous D) ΔSsurr = +12.67 kJ/K, reaction is not spontaneous E) ΔSsurr = -3.18 kJ/K, it is not possible to predict the spontaneity of this reaction without more information.  
Calculate the standard entropy of fusion of ethanol at its melting point 159 K. The standard molar enthalpy of fusion of ethanol at its melting point is 5.02 kJ · mol−1. 1. −44.0 J · K−1· mol−1 2. −5.02 kJ · K−1· mol−1 3. −31.6 J · K−1· mol−1 4. +5.02 kJ · K−1· mol−1 5. +31.6 J · K−1· mol−1
Calculate the change in the standard entropy of the system, ΔS°, for the synthesis of ammonia from N2(g) and H2(g) at 298 K.  S° (N2) = 191.5 J/mol•K S° (H2) = 130.6 J/mol•K S° (NH3) = 192.5 J/mol•K
Consider the reaction of N2O5 at 25°C for which the following data are relevant: 2 N2O5 (g) → 4 NO2 (g) + O2 (g) Substance             ΔH°f                               S°              N 2O5                    11.29 kJ/mol             355.3 J/K mol               NO 2                     33.15 kJ/mol             239.9 J/K mol               O 2                                   ?                     204.8 J/K mol   What is ΔS° for the reaction (in J/K)? a) 89.5 b) 249.2 c) 453.8 d) 249.2 e) -115.6
Calculate ΔS°rxn for the following reaction. The S° for each species is shown below the reaction. C2H2(g) + H2(g) → C2H4(g) S°(J/mol·K)              200.9             130.7               219.3 A) +112.3 J/K B) +550.9 J/K C) -550.9 J/K D) +337.1 J/K E) -112.3 J/K    
A system releases 900 J of heat to the surroundings, which are at a constant 27 ◦C. What is ∆S of the surroundings? 1. 33.3 J · K−1 2. −3 J · K−1 3. 3 J · K−1 4. −33.3 J · K−1
HI has a boiling point of –35.4 oC with a standard enthalpy of vaporization of 21.16 kJ/mol. Calculate the standard entropy of vaporization of HI. a) 598 J/K·mol b) 68.6 J/K·mol c) 75.2 J/K·mol d) 0.068 J/K·mol e) 89.0 J/K·mol
Which of the following reaction(s) is/are predicted to have favorable ∆S ̊rxn? a) N2 (g) + 3 H2 (g) → 2 NH3 (g) b) H2O (l) → H2O (s) c) C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) d) Both a and b e) None of the above
Benzene has a ΔHvap = 33.90 kJ/mol and a ΔSvap = 96.4 J/mol-K. What is the vaporization temperature of Benzene in Celsius? A. −273 B. 78.5 C. 352 D. 2570 E. 2840
The compound benzoic acid, C6H5COOH, melts at 122.4 ̊C. If the enthalpy of fusion of this compound is 17.3 kJ/mol, what is its entropy of fusion? a. 31.3 J/mol·K b. 34.1 J/mol·K c. 38.0 J/mol·K d. 40.2 J/mol·K e. 43.8 J/mol·K
Consider the following figure of four processes from the initial state. The substances are in gas phase initially. Which process(es) would result in an entropy increase?   A. (1) and (2)  B. (1) and (3) C. only (3) D. (1), (2), and (4) E. only (4)  
Balance the following reaction and then solve for the ∆S (J/K-mol) for this reaction. Li (g) + H2(g) → LiH (s) With S° (J/K-mol) value of LiH = 20.0          Li = 138.7        H   2 = 130.6 A. −368.0 B. −249.3 C. −106.8 D. 249.3 E. 368.0  
  Explain the following plot:
Of the following descriptions, how many (the total number) would increase entropy? Sublimation of sodium; C2H6 (g) → C2H2 (g) + 2 H2(g); Heating hexane; Boiling water A.none of them B. 1 C. 2 D. 3 E. All of them
Consider the following processes (Treat all gases as ideal). 1. Nitrogen gas is compressed isothermally to one half its original volume. 2. Carbon dioxide is allowed to expand isothermally to 10 times its original volume. 3. A glass of water loses 100 J of energy reversibly at 30°C. 4. The temperature of one mole of helium is increased 25°C at constant pressure. 5. The pressure of one mole of oxygen gas is allowed to double isothermally.   Which of these processes leads to an increase in entropy?   a) 1 and 4         b) 5         c) 3 and 5         d) 2 and 4         e) 1 and 2  
For which process is the entropy change per mole the largest at constant temperature?  (A) H2O(l) → H2O(g) (B) H2O(s) → H2O(g) (C) H2O(s) → H2O(l) (D) H2O(l) → H2O(s)
Which of the following processes have a positive entropy term?   A. Synthesis of ammonia from nitrogen and hydrogen gas. B. Creation of sodium bicarbonate from gaseous water, carbon dioxide and sodium carbonate C. Freezing of methanol D. Creation of carbon monoxide and hydrogen gas from gaseous methane and gaseous water E. All of the above have a positive entropy term. 
Which of the following would have the   highest value of absolute entropy per mole? a) Water at 50 oC b) Water at 10 oC c) Ice at -10 oC d) 1 M NaCl at 50 oC e) 1 M NaCl at 10 oC  
Which of the following phase changes is correctly paired with the sign of its change in entropy and its change in enthalpy?
What are the signs for the change in enthalpy and change in entropy when a system undergoes the phase transition of freezing? A. ∆H < 0 , ∆S < 0 B. ∆H > 0 , ∆S > 0 C. ∆H < 0 , ∆S > 0 D. ∆H > 0 , ∆S < 0
Which of the following statements describes situations where entropy increases: I. Increase in number of gas particles present II. Separated gas particles in a flask being allowed to mix III. Gas particles undergo deposition   A. Only I                 B. Only II                 C. Only III               D. I and II               E. All three
Rank the following compounds in order of increasing entropy at 25°C? A. MgCO3 (s) B. CO (g) C. Ni (s) D. H2O (I) E. CH3OH (I)
Would you expect the entropy of the system to  increase or decrease for each of the following processes: a. CaCO3 (s) → CaO (s) + CO2 (g)       ________________   b. H2O (g) → H2O (l)                             ________________
When temperature is increased and pressure is held fixed across a phase change which of the following statements is true? A. Entropy is negative and enthalpy is positive. B. Entropy is negative and enthalpy is negative. C. Entropy is positive and enthalpy is positive. D. Entropy is positive and enthalpy is negative.
Coal is a major source of energy that can be converted from its solid, raw form to a gaseous phase of fuel. This is accomplished by the water gas reaction: C (s) + H2O (g)      →      CO (g) + H2 (g) What is the entropy value for the water gas reaction shown above?   A. – 268 kJ/mol B. – 134 kJ/mol C. 0 kJ/mol D. +134 kJ/mol
Which of the following reactions would be entropically favored?   A) Precipitation of ions from a supersaturated solution. B) Deposition of gaseous carbon dioxide. C) Ionization of an organic compound. D) The fusion of inorganic nuclides. 
Arrange the following substances in the order of increasing entropy at 25° C.               CO 2 (s)         Kr (g)         S  8 (s)         O 3 (g)         H 2O (l)         H 2S (l)
Which of the following statements describes situations where entropy increases: I.  Increase in number of gas particles present II.  Separated gas particles in a flask being allowed to mix III.  Gas particles undergo deposition   A.  Only I                  B.  Only II                  C.  Only III                   D.  I and II                  E.  All three
Consider the following processes (at 298 K) given below and determine for which is ΔS positive?
Consider the following reaction at constant pressure. Use the information here to determine the value of ∆Ssurr at room temperature. Predict whether or not this reaction will be spontaneous at this temperature. N2 (g) + 2 O2 (g) → 2 NO2 (g)              ∆H° = + 66.4 kJ ∆Ssurr = - 223J/K, not spontaneous ∆Ssurr = + 265 J/K, not spontaneous ∆Ssurr = + 223 J/K, is spontaneous ∆Ssurr = - 66.4 J/K, not spontaneous ∆Ssurr = - 66.4 J/K, not possible to predict the spontaneity 
Predict the sign on ΔS° for the following reactions i. 2 KClO4 (s) → 2 KClO3(s) + O2(g) ii. Propanol condenses at room temperature iii. CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)            Reaction i          Reaction ii          Reaction iii A.          +                            +                           - B.           -                             +                          + C.           +                             -                          0  D.            -                            +                          0 E.            +                            -                          -   
Rank the standard molar entropy of the following from lowest to highest. 1. H2O2 (l) 2. H2O (g) 3. H2O (l) 4. H2O2 (aq) a) 4 < 1 < 3 < 2     b) 1 < 3 < 4 < 2 c) 3 < 1 < 4 < 2 d) 2 < 4 < 3 < 1 e) 1 < 3 < 2 < 4 
Would you expect the entropy of the system to  increase or decrease for each of the following processes: a. N2 (g) + 3H2 (g) → 2NH3 (g)       ________________   b. H2O (l) → H2O (g)                        ________________
When most elastomeric polymers (e.g., a rubber band) are stretched, the molecules become more ordered, as illustrated here: Suppose you stretch a rubber band.Do you expect the entropy of the system to increase or decrease?
For which of the following processes does the entropy of the system increase? (a) the ripening of a banana,(b) dissolution of sugar in a cup of hot coffee, (c) the reaction of nitrogen atoms to form N2 molecules at 25 and 1 atm, (d) lightning, (e) formation of CH4 and O2 molecules from CO2 and H2O at room temperature and 1 atm of pressure?
Predict the sign of the entropy change of the system for each of the following reactions.(a) N2 (g) + 3H2 (g)  →  2NH3 (g) (b) CaCO3(s)  →  CaO(s) + CO2(g) (c) 3C2H2(g)  →  C6H6(g) (d) Al2O3(s) + 3H2 (g)  →  2Al(s) + 3H2O(g)
The accompanying diagram shows how the free energy, G, changes during a hypothetical reaction A(g) +B(g) →  C(g). On the left are pure reactants A and B, each at 1 atm, and on the right is the pure product, C, also at 1 atm. Indicate whether each of the following statements is true or false. The entropy change for this reaction is positive.
The following processes were all discussed in Chapter 18, "Chemistry of the Environment" in the textbook.Estimate whether the entropy of the system increases or decreases during each process.(a) photodissociation of O2 (g), (b) formation of ozone from oxygen molecules and oxygen atoms, (c) diffusion of CFCs into the stratosphere, (d) desalination of water by reverse osmosis.
In chemical kinetics, the entropy of activation is the entropy change for the process in which the reactants reach the activated complex.Predict whether the entropy of activation for a bimolecular process is usually positive or negative.
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.Sc(s) and Sc(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.NH3(g) and NH3(aq)
Which process has the larger entropy change: melting ice or boiling water?
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.1 mol O2(g) and 2 mol O3(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.C (graphite) and C (diamond)
In each of the following pairs, which compound would you expect to have the higher standard molar entropy?C2 H2 (g) or C2 H6 (g);
In each of the following pairs, which compound would you expect to have the higher standard molar entropy?CO2 (g) or CO(g).
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.He(l) or He(g).
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.He(g) at 5 atm pressure or He(g) at 1.8 atm pressure.
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.1 mol of Ne(g) in 16.0 L or 1 mol of Ne(g) in 1.60 L.
For each of the following pairs, predict which substance has the higher entropy per mole at a given temperature.CO2(g) or CO2(s).
When most elastomeric polymers (e.g., a rubber band) are stretched, the molecules become more ordered, as illustrated here: Suppose you stretch a rubber band.Try this experiment: Stretch a rubber band and wait a moment. Then place the stretched rubber band on your upper lip, and let it return suddenly to its unstretched state (remember to keep holding on). What do you observe?
Do you need to specify the temperature to calculate the entropy change? Explain.
The pressure on 0.680 mol of neon gas is increased from 0.760 atm to 1.15 atm at 100 oC.Do you need to specify the temperature to calculate the entropy change? Explain.
If you are told that the entropy of a system is zero, what do you know about the system?
Indicate whether each statement is true or false.Unlike enthalpy, where we can only ever know changes in H, we can know absolute values of S.
What is the precise definition of entropy? What is the significance of entropy being a state function?
Why does the entropy of a gas increase when it expands into a vacuum?
Based on its fundamental definition, explain why entropy is a measure of energy dispersion.
What happens to the entropy of a sample of matter when it changes state from a solid to a liquid?
What happens to the entropy of a sample of matter when it changes state from a liquid to a gas?
Why is the standard entropy of a substance in the gas state greater than its standard entropy in the liquid state?
How does the standard entropy of a substance depend on its molar mass?
How does the standard entropy of a substance depend on its molecular complexity?
How does the entropy of the system change when a solid melts, a gas liquefies, a solid sublimes?
Entropy decreases when NO(g) is oxidized by O2(g) to NO2(g).What major factor leads to a decrease in entropy as the reaction shown takes place?
Entropy increases with increasing temperature.Why does the plot show vertical jumps at the melting and boiling points?
How does the molar entropy of a substance change with increasing temperature?
You may want to reference (Pages 437 - 438) Section 11.1 while completing this problem.List the three states of matter in order of increasing molecular disorder.
Methanol (CH3OH) can be made by the controlled oxidation of methane: CH4(g) + O2(g)  →  CH3OH(g)Use data in Appendix C in the textbook to calculate S S for this reaction.
Consider the following three reactions. For each of the reactions, use data in Appendix C in the textbook to calculate H H G G S S , Delta G ^circ, and Delta S ^circ at 25 ^circ { m C}.Calculate S S (s) + 2Cl2(g)  →  TiCl4(g) for { m Ti}(s) + 2,{ m Cl}_2(g) ightarrow { m TiCl}_4(g)
The pressure on 0.680 mol of neon gas is increased from 0.760 atm to 1.15 atm at 100 oC.If the final pressure on the gas is 1.15 atm , calculate the entropy change for the process.
How can you calculate the standard entropy change for a reaction from tables of standard entropies?
If energy can flow in and out of the system to maintain a constant temperature during the process, what can you say about the entropy change of the surroundings as a result of this process?
Use data in Appendix C to estimate the boiling point of benzene, C6H6(l).
True or false: An endothermic process increases the entropy of the surroundings. ________
Predict how the entropy of the substance is affected in the following processes. CH4(g, 125°c) → CH4(g, 200°C)  a) increases b) decreases c) remains the same
For the following questions circle the correct answer. There is one and only one correct answer. The substance with the largest value for entropy (at T = 25.0 °C and p = 1.00 atm). a) CH3CH2CN(l) b) CH3CN(I) c) CH3CH2CN(g) d) CH3CN(g)
Why does the solubility of NaCl only increase slowly with water temperature?A. ΔSsol > 0 but small in magnitudeB. ΔSsol < 0 but small in magnitudeC. ΔHsol > 0 but small in magnitudeD. ΔHsol < 0 but small in magnitudeE. it has a very large lattice energy
Consider the following reaction at 298 K 2Al (s) + 3Cl2 (g) → 2AlCl3 (s)         H=-1408 KJ Calculate the following quantities: (a) Ssys= ?  (b) Ssurr= ? (c) Suniv= ?
Using the following data, calculate ΔSfus and ΔSvap for HBr.Determine the entropy change when 4.80 mol of HBr (f) freezes at atmospheric pressure. 
CO(NH2)2(aq) + H2O(l) → CO2(g) +2NH3(g) ΔS° = +354.8 J/mol*KGiven the data below, calculate the ΔS° f for UreaSubstance S° (J/molK)H2O (l) 69.96CO2 (g) 213.6NH3 (g) 192.5 
Which of the following reactions have a positive ΔS rxn?  a) 2 A(g) + B(s) → 3 C(g) b) 2 A(g) + B(g) → C(g) c) A(g) + B(g) → C(g) d) 2 A(g) + 2 B(g) → 5 C(g) e) More than one of the above
ΔS is positive for the reaction _________________.a. 2NO(g) + O 2(g) → 2NO2(g)b. 2N2(g) + 2H2(g) → 2NH3(g)c. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) d. Mg(s) + Cl2(g) → MgCl2(s)e. C2H4(g) + H2(g) → C2H6(g)
The enthalpy of vaporization of acetone is 31.3 kJ/mol, and its boiling point is 56.3°C. What is the entropy change for the vaporization (boiling) of acetone?
Predict the sign of the entropy change, ΔS°, for each of the reaction displayed. Drag the appropriate items to their respective bins.
The ΔH°vap for pure water is 40.65 kJ/mol. Calculate the ΔS°vap for pure water.
The enthalpy of vaporization of methanol is 35.27 kJ mol-1 at its boiling point of 64.1°Ca. Calculate the entropy of vaporization of methanol at this temperature.b. Calculate the entropy of surroundings.
Which of the following statements describes situations where entropy increases:                                     I.  Increase in number of gas particles present                                     II.  Separated gas particles in a flask being allowed to mix                                     III.  Gas particles undergo deposition   A.  Only I              B.  Only II        C.  Only III        D.  I and II       E.  All three
Predict the sign of the entropy change, ΔS°, for each of the reaction displayed. i) 2NO2 (g) → N2 (g) + 2O2 (g) ii) C5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (g) iii) 2NaClO3 (s) → 2NaCl (s) + 3O2 (g) iv) 2Na (s) + Cl2 (g) → 2NaCl (s) v) CH3OH (l) → CH3OH (g)
HI has a boiling point of –35.4°C with a standard enthalpy of vaporization of 21.16 kJ/mol. Calculate the standard entropy of vaporization of HI.a) 598 J/K·molb) 68.6 J/K·molc) 75.2 J/K·mold) 0.068 J/K·mole) 89.0 J/K·mol
Which of the following reactions have a positive delta S rxn? Check all that apply.
How many of the following processes represent an increase in entropy:* Water is heated in the microwave from 23 Celsius to 90 Celsius* The sublimation of I2* CO 2 gas is dissolved in water to make a carbonated beverage* N2O4 (g) → 2 NO2 (g)A. noneB. oneC. twoD. threeE. all four
The thermodynamic quantity that expresses the degree of disorder in a system is _________. a. enthalpy b. internal energy c. bond energy d. entropy e. heat flow
Which one of the following processes produces a decrease in the entropy of the system? a. boiling water to form steam b. dissolution of solid KCl in water c. mixing of two gases into one container d. freezing water to form ice e. melting ice to form water 
ΔS is positive for the reaction _______. a. CaO(s) + CO2(g) → CaCO3(s) b. N2(g) + 3H2(g) → 2NH3(g) c. 2SO3(g) → 2SO2(g) + O2(g) d. Ag+(aq) + Cl-(aq)→AgCl(s) e. H2O(l) → H2O(s)   
For one mole of substance at a given temperature, select the member in each pair with the higher entropy.a. P2(g), P4(g)b. CaF2(s), BaCl2(s)c. CuSO4(s), CuSO4•5H2O(s)
Which of the following reaction(s) is/are predicted to have favorable ∆S°rxn? a) N2 (g) + 3 H2 (g) → 2 NH3 (g) b) H2O (l) → H2O (s) c) C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) d) Both a and b e) None of the above
For a given compound, list the decreasing order of entropy for a solid, liquid, and gas.a. solid > gas > liquidb. liquid > solid > gasc. gas > liquid > solidd. gas > solid > liquide. solid > liquid > gas
Nitric oxides, NO and NO2, contribute to air pollution, acid rain, and the depletion of the ozone layer. After NO forms in the combustion chamber of an automobile engine, it reacts further with oxygen to form NO2. The reaction is given by 2NO(g) + O2(g) → 2NO2(g) Calculate ΔSrxn∘ for the reaction.
Which of the following processes involves a decrease in entropy? a. the decomposition of NH 3 (g) b. the condensation of steam c. the sublimation of CO2  d. the evaporation of ethanol e. the dissolution of NH4NO3(s) in water f.  I2 at 90oC and 5.0 atm  →  I2 at 50oC and 10.0 atm g. NH4Cl(s) → HCl(g) +  NH3(g) h. CH4(g)  +  2 O2(g)  →  CO2(g)  +  2 H2O(l) 
Which reaction is/are predicted to have a negative entropy of reaction? a) CH3CH2OH (s) → CH3CH2OH (l) b) CH3CH2OH (l, 10 ̊C) → CH3CH2OH (l, 50 ̊C) c) CH3CH2OH (l, 50 ̊C) → CH3CH2OH (l, 10 ̊C) d) Both a and b e) Both a and c
Predict how the entropy of the substance is affected in the following process:                                            Ar(l) → Ar(g)  a) increases b) decreases  
Calculate ΔS∘rxn for this balanced chemical equation. 2NO(g) + O2(g) → 2NO2(g) Express your answer to one decimal place and include the appropriate units.
Given the standard entropy values in the table below, determine the standard entropy change of the reaction below that produces 10.0 g of metallic Cu. 
Predict how the entropy of the substance is affected in the following process? Br2 (l, 1 bar, 25°celcius) yields Br2 (g, 1 bar, 25°Celsius) a) Increases b) decreases c) stays the same
Using the data in the table, calculate the standard entropy changes for the following reactions at 25°.
Given the values of ΔH∘rxn, ΔS∘rxn, and T below, determine ΔSuniv. a. ΔH∘rxn = 84 kJ , ΔS∘rxn = 144 J/K , T = 303 K b. ΔH∘rxn = 84 kJ , ΔS∘rxn = 144 J/K , T = 762 K c. ΔH∘rxn = 84 kJ , ΔS∘rxn = −144 J/K , T = 303 K d. ΔH∘rxn = − 84 kJ , ΔS∘rxn = 144 J/K , T = 406 K
Determine the sign of ΔSsys in each of the following processes: Water boiling
Determine the sign of ΔSsys in each of the following processes: Water freezing
Determine the sign of ΔSsys in each of the following processes:
Determine the sign of ΔSsys in each of the following processes: dry ice subliming
Determine the sign of ΔSsys in each of the following processes: dew forming
Determine the sign of ΔSsys in each of the following processes:
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions.a. Mg(s) + Cl2(g) → MgCl2(s)b. 2 H2S(g) + 3 O2(g) → 2 H2O(g) + 2 SO2(g)c. 2 O3(g) → 3 O2(g)d. HCl(g) + NH3(g) → NH4Cl(s)
Consider two processes: sublimation of I2 (s) and melting of I2 (s) (Note: the latter process can occur at the same temperature but somewhat higher pressure).I2(s) ⟶ I2(g)                    I 2(s) ⟶ I2(l)Is ΔS  positive or negative in these processes? In which of the processes will the magnitude of the entropy change be greater?
Predict the sign of the entropy change for the following process: An ice cube is warmed to near its melting point.
Predict the sign of the entropy change for the following process: Exhaled breath forms fog on a cold morning.
Predict the sign of the entropy change for the following process: Snow melts.
Predict the sign of the entropy change for the following process. Give a reason for your prediction.Pb2+(aq) + S2−(aq) ⟶ PbS(s)
Predict the sign of the entropy change for the following process. Give a reason for your prediction.2 Fe(s) + 3/2 O2(g) ⟶ Fe2O2(s)
Predict the sign of the entropy change for the following process. Give a reason for your prediction.2 C6H14(l) + 19 O2(g) ⟶ 14 H2O(g) + 12 CO2(g)
Write the balanced chemical equation for the combustion of methane, CH4(g), to give carbon dioxide and water vapor. Explain why it is difficult to predict whether ΔS is positive or negative for this chemical reaction.
Write the balanced chemical equation for the combustion of benzene, C6H6(l), to give carbon dioxide and water vapor. Would you expect ΔS to be positive or negative in this process?
Predict the sign of ΔS surr for the following process.a. H2O(l) → H2O(g)
Predict the sign of ΔS surr for the following process.b. I2(g) → I2(s)
Predict the sign of ΔS sys for the process: (a) A piece of wax melts.
Predict the sign of ΔS sys for the process: (b) Silver chloride precipitates from solution.
Predict the sign of ΔS sys for the process: (c) Dew forms on a lawn in the morning.
Predict the sign of ΔS sys for the process: (a) Gasoline vapors mix with air in a car engine.
Predict the sign of ΔS sys for the process: (b) Hot air expands.
Predict the sign of ΔS sys for the process: (c) Humidity condenses in cold air.
Predict the sign of ΔS sys for the process: (a) Alcohol evaporates.
Predict the sign of ΔS sys for the process: (b) A solid explosive converts to a gas.
Predict the sign of ΔS sys for the process: (c) Perfume vapors diffuse through a room.
Predict the sign of ΔSsys for the following process:(a) A pond freezes in winter.
Predict the sign of ΔSsys for the following process:(b) Atmospheric CO2 dissolves in the ocean.
Predict the sign of ΔSsys for the following process:(c) An apple tree bears fruit.
Without using Appendix B, predict the sign of ΔS° for 2K(s) + F 2(g) ⟶ 2KF(s)
Predict the sign of sys for each of the following processes.
Without using Appendix B, predict the sign of ΔS° for NH 3(g) + HBr(g) ⟶ NH 4Br(s)
Without using Appendix B, predict the sign of ΔS° for NaClO 3(s) ⟶ Na+(aq) + ClO3−(aq)
Predict the sign of ΔS for each process.(a) the boiling of water(b) I2(g) → I2(s)(c) CaCO3(s)→ CaO(s) + CO2(g)
Without using Appendix B, predict the sign of ΔS° for H 2S(g) + 1/2O2(g) ⟶ 1/8S8(s) + H2O(g)
Without using Appendix B, predict the sign of ΔS° for HCl( aq) + NaOH(aq) ⟶ NaCl(aq) + H2O(l)
Which of the following processes have a ΔS > 0? a. 2NH3(g) + CO2(g) → NH2CONH2(aq) + H2O(l) b. lithium fluoride forms from its elements c. 2HF(g) → H2(g) + F2(l) d. potassium iodide dissolves in pure water
Without using Appendix B, predict the sign of ΔS° for 2NO 2(g) ⟶ N2O4(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Without using Appendix B, predict the sign of ΔS° for CaCO 3(s) + 2HCl(aq) ⟶ CaCl2(aq) + H2O(l) + CO2(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Without using Appendix B, predict the sign of ΔS° for 2NO(g) + O 2(g) ⟶ 2NO2(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Consider these three changes in the possible distributions of six gaseous particles within three interconnected boxes. Which change has a positive ΔS?
Without using Appendix B, predict the sign of ΔS° for 2KClO 3(s) ⟶ 2KCl(s) + 3O2(g)
Predict the sign of ΔS° for each of the following changes. Assume all equations are balanced.
Which of the following reactions (or processes) are expected to have a negative value for ΔS°?a. SiF6(aq) + H2(g) → 2HF(g) + SiF4(g)b. 4Al(s) + 3O 2(g) → 2Al2O3(s)c. CO(g) + Cl 2(g) → COCl2(g)d. C2H4(g) + H2O(l) → C2H5OH(l)e. H2O(s) → H2O(l)
Predict the sign of ΔS° for each of the following changes. a. K (s) + 1/2Br2 (g) → KBr (s)
Predict the sign of ΔS° for each of the following changes. b. N2 (g) + 3H2 (g) → 2NH3 (g)
Predict the sign of ΔS° for each of the following changes. c. KBr (s) → K+ (aq) + Br - (aq)
Which reaction is most likely to have a positive ΔSsys?a) SiO2(s) + 3 C(s) → SiC(s) + 2 CO(g)b) 6 CO2(g) + 6 H2O(g) → C6H12O6(s) + 6 O2(g)c) CO(g) + Cl2(g) → COCl2(g)d) 3 NO2(g) + H2O(l) → 2 HNO3(l) + NO(g)
Predict the sign of ΔS° for each of the following changes. d. KBr (s) → KBr (l)
Without using Appendix B, predict the sign of ΔS° for Ag +(aq) + Cl −(aq) ⟶ AgCl(s)
Without using Appendix B, predict the sign of ΔS° for KBr(s) ⟶ KBr(aq)
Without using Appendix B, predict the sign of ΔS° for the following:
Predict the sign of ΔS for the process: C 2H5OH(g) (350 K and 500 torr) ⟶ C2H5OH(g) (350 K and 250 torr)
Predict the sign of ΔS for the process: N 2(g) (298 K and 1 atm) ⟶ N2(aq) (298 K and 1 atm)
Predict the sign of ΔS for the process: O 2(aq) (303 K and 1 atm) ⟶ O 2(g) (303 K and 1 atm)
When heated, the DNA double helix separates into two random coil single strands. When cooled, the random coils reform the double helix: double helix ⇌ 2 random coils.(a) What is the sign of ΔS for the forward process? Why?
Predict the sign of ΔS for the process: O 2(g) (1.0 L at 1 atm) ⟶ O 2(g) (0.10 L at 10 atm)
Predict the sign of ΔS for the process: Cu(s) (350°C and 2.5 atm) ⟶ Cu(s) (450°C and 2.5 atm)
Predict the sign of ΔS for the process: Cl 2(g) (100°C and 1 atm) ⟶ Cl 2(g) (10°C and 1 atm)
Predict the sign of S accompanying reaction on the figure.
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions:2 KClO3(s) → 2 KCl(s) + 3 O2(g)
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions:CH2=CH2(g) + H2(g) → CH3CH3(g)
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions: Na(s) + 1/2 Cl2(g) → NaCl(s)
Does the entropy of the system increase, decrease, or stay the same for each of the following conditions.
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions: N2(g) + 3 H2(g) → 2 NH3(g)
Without doing any calculations, determine the sign of ΔSsys for each of the following chemical reactions.a. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), ΔH˚rxn = –2044 kJb. N2(g) + O2(g) → 2 NO(g), ΔH˚rxn = +182.6 kJc. 2 N2(g) + O2(g) → 2 N2O(g), ΔH˚rxn  = +163.2 kJd. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g), ΔH˚rxn = –906 kJ
Without doing any calculations, determine the sign of ΔSsurr for each of the following chemical reactions.a. C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), ΔH˚rxn = –2044 kJb. N2(g) + O2(g) → 2 NO(g), ΔH˚rxn = +182.6 kJc. 2 N2(g) + O2(g) → 2 N2O(g), ΔH˚rxn  = +163.2 kJd. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g), ΔH˚rxn = –906 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.2 CO(g) + O2(g) ⇌ 2 CO2(g), ΔH˚rxn = –566.0  kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.2 NO2(g) → 2 NO(g) + O2(g), ΔH˚rxn = +113.1 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.2 H2(g) + O2(g) → 2 H2O(g), ΔH˚rxn = –483.6 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below.CO2(g) → C(s) + O2(g), ΔH˚rxn = +393.5 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.2 CO(g) + O2(g) → 2 CO2(g), ΔH˚rxn = –556.0 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.2 NO2(g) → 2 NO(g) + O2(g), ΔH˚rxn = +113.1 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.2 H2(g) + O2(g) → 2 H2O(g), ΔH˚rxn = –483.6 kJ
Without doing any calculations, determine the sign of ΔSsys and ΔSsurr for each of the chemical reactions below. In addition, predict under what temperatures (all temperatures, low temperatures, or high temperatures), if any, the reaction will be spontaneous.CO2(g) → C(s) + O2(g), ΔH˚rxn = +393.5 kJ
Which process will decrease entropy? a. SO2(l) → SO2(g) b. H2O(g) → H2O(l) c. CaCO3(s) → CaO(s) + CO2(g) d. 2Cl2O(g) → 2Cl2(g) + O2(g)
Given the values of ΔH∘rxn, ΔS∘rxn, and T below, determine ΔSuniv. a) ΔH∘rxn = 87 kJ , ΔS∘rxn = 146 J/K , T= 296 K, will this be spontaneous or not spontaneous? b) ΔH∘rxn = 87 kJ , ΔS∘rxn = 146 J/K , T= 762 K, will this be spontaeous or not spontaneous? c) ΔH∘rxn = 87 kJ , ΔS∘rxn = −46 J/K , T= 296 K, will this be spontaneous or not spontaneous? d) ΔH∘rxn = −87 kJ , ΔS∘rxn = 146 J/K , T= 390 K, will this be spontaneous or not spontaneous?
Entropy is a measure of a. free energy b. the heat of a reaction c. molecular randomness d. the rate of a reaction
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.PCl3(g); PCl5(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH3CH2CH2CH3(g); SO2(g)
Rank the contents of the following containers in order of decreasing entropy.
Rank the following substances in order of decreasing standard molar entropy (S˚).a. I2(g); F2(g); Br2(g); Cl2(g)b. H2O(g); H2O2(g); H2S(g)c. C(s, graphite); C(s, diamond); C(s, amorphous)
Arrange the following set of systems in order of increasing entropy. Assume one mole of each substance and the same temperature for each member of a set.H2(g), HBrO4(g), HBr(g)
Arrange the following set of systems in order of increasing entropy. Assume one mole of each substance and the same temperature for each member of a set.H2O(l), H2O(g), H2O(s)
Arrange the following set of systems in order of increasing entropy. Assume one mole of each substance and the same temperature for each member of a set.He(g), Cl2(g), P4(g)
Indicate which substance in the given pair has the higher entropy value. Explain your choice.C2H5OH(l) or C3H7OH(l)
Indicate which substance in the given pair has the higher entropy value. Explain your choice.C2H5OH(l) or C2H5OH(g)
Indicate which substance in the given pair has the higher entropy value. Explain your choice.2 H(g) or H(g)
Which of the following involve an increase in the entropy of the system?a. melting of a solidb. sublimationc. freezingd. mixinge. separationf. boiling
Arrange these gases in order of decreasing standard molar entropy: Rank from largest to smallest. Cl2 SO3 Kr
Arrange these gases in order of decreasing standard molar entropy: SO3, Kr, Cl2.
For each of the following pairs of substances, which substance has the greater value of S°?a. Cgraphite(s) or Cdiamond(s)
Arrange the gases – F2, Ar, and CH3F – in order of increasing standard entropy (S˚) at 298 K.
For each of the following pairs of substances, which substance has the greater value of S°?b. C2H5OH (l) or C2H5OH (g)
For each of the following pairs of substances, which substance has the greater value of S°?c. CO2 (s) or CO2 (g)
For each of the following pairs, which substance has the greater value of S?a. N2O (at 0 K) or He (at 10 K)
For each of the following pairs, which substance has the greater value of S?b. N2O(g) (at 1 atm, 25°C) or He(g) (at 1 atm, 25°C)
For each of the following pairs, which substance has the greater value of S?c. NH3 (s) (at 196 K) → NH3 (l) (at 196 K)
Predict which substance has greater molar entropy. Explain.(a) Butane CH3CH2CH2CH3(g) or 2-butene CH3CH=CHCH3(g)(b) Ne(g) or Xe(g)(c) CH4(g) or CCl4(l)
Predict which substance has greater molar entropy. Explain.(a) NO2(g) or N2O4(g)(b) CH3OCH3(l) or CH3CH2OH(l)(c) HCl(g) or HBr(g)
Predict which substance has greater molar entropy. Explain.(a) CH3OH(l) or C2H5OH(l)(b) KClO3(s) or KClO3(aq)(c) Na(s) or K(s)
Predict which substance has greater molar entropy. Explain.(a) P4(g) or P2(g)(b) HNO3(aq) or HNO3(l)(c) CuSO4(s) or CuSO4·5H2O(s)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) Graphite, diamond, charcoal
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) Ice, water vapor, liquid water
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) O2, O3, O atoms
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) Glucose (C6H12O6), sucrose (C12H22O11), ribose (C5H10O5)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) CaCO3, Ca + C + 3/2O2, CaO + CO 2
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) SF6(g), SF4(g), S2F10(g)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) ClO4−(aq), ClO2−(aq), ClO3−(aq)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) NO2(g), NO(g), N2(g)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) Fe2O3(s), Al2O3(s), Fe3O4(s)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(a) Mg metal, Ca metal, Ba metal
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(b) Hexane (C6H14), benzene (C6H6), cyclohexane (C6H12)
Without consulting Appendix B, arrange the group in order of increasing standard molar entropy (S°). Explain.(c) PF2Cl3(g), PF5(g), PF3(g)
Kyanite, sillimanite, and andalusite all have the formula Al 2SiO5. Each is stable under different conditions (see the graph below). At the point where the three phases intersect:(c) Which mineral, if any, has the highest entropy?
Rank each of the following in order of decreasing standard molar entropy (S˚).a. NH3(g); Ne(g); SO2(g); CH3CH2OH(g); He(g)b. H2O(s); H2O(l); H2O(g)c. CH4(g); CF4(g); CCl4(g)
Rank these systems in order of decreasing entropy. Rank from highest to lowest entropy. To rank items as equivalent, overlap them. A) 1 mol carbon tetrafluoride gas at 273k 40L B) 1 mol krypton gas at 273K 40L C) 1/2 mol krypton gas at 100k 20L D) 1 mol krypton gas at 273K 20L E) 1/2 mol krypton liquid at 100K F) 1 mol fluorine gas 273 K 40L G) 1/2 mol krypton gas at 273K 20L
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CO(g); CO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH3OH(l); CH3OH(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.Ar(g); CO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH4(g); SiH4(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CO2(g);  CH3CH2CH3(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.NaBr(s); NaBr(aq)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.C6H6(l) and C6H6(g);
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CO(g); CO2(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance. CO(g) and CO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH3OH(l); CH3OH(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance.1 mol N2O4(g) and 2 mol NO2(g);
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.Ar(g); CO2(g)
Predict which member of each of the following pairs has the greater standard entropy at 25 oC. Use Appendix C to find the standard entropy of each substance. HCl(g) and HCl(aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH4(g); SiH4(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.NO2(g); CH3CH2CH3(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.NaBr(s); NaBr(aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.NaNO3(s); NaNO3 (aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH4(g); CH3CH3(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 1 mol of O2(g)  at 300 oC, 0.01 atm and 1 mol of O3(g) at 300 oC, 0.01 atm.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.Br2(l); Br2(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 1 mol of H2O(g) at 100 oC, 1 atm and 1 mol of H2O(l) at 100 oC, 1 atm.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.Br2(g); F2(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 0.5 mol of N2(g)  at 298 K, 20-L volume and 0.5 CH4(g)  at 298 K, 20-L volume.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.PCl3(g); PCl5(g)
For each of the following pairs, predict which substance possesses the larger entropy per mole.Compare 100 g Na2SO4(s) at 30 oC and 100 g Na2SO4(aq) at 30 oC.
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C.CH3CH2CH2CH3(g); SO2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.NaNO3(s); NaNO3(aq)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.CH4(g); CH3CH3(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.Br2(l); Br2(g)
For each pair of substances, choose the one that you expect to have the higher standard molar entropy (S˚) at 25 ˚C. Explain the reasons for your choice.Br2(g); F2(g)
Calculate ΔSfus and ΔSvap for Na.
What is the difference between ΔS, ΔS°, and ΔS°298 for a chemical change?
At room temperature, the entropy of the halogens increases from I2 to Br2 to Cl2. Explain.
Is the statement true or false? If false, correct it.(e) If a process increases the freedom of motion of the particles of a system, the entropy of the system decreases.
The diagram shows the variation in entropy with temperature for a substance that is a gas at the highest temperature shown.What processes correspond to the entropy increases along the vertical lines labeled 1 and 2 in this diagram?
The diagram shows the variation in entropy with temperature for a substance that is a gas at the highest temperature shown.Why is the entropy change for process 2 larger than that for process 1?
One reaction used to produce small quantity of pure H 2 isCH3OH(g) ⥫⥬ CO(g) + 2H2(g)(a) Determine ΔH° and ΔS° for the reaction at 298 K.
A reaction that occur in the internal combustion engine isN2(g) + O2(g) ⥫⥬ 2NO(g)(a) Determine ΔH° and ΔS° for the reaction at 298 K.
Ethene (C2H4) can be halogenated by the following reaction: C2H4(g) + X2(g) ⇌ C2H4X2(g), where X2 can be Cl2, Br2, or I2.Use the thermodynamic data given below to calculate ΔS˚ for the halogenation reaction by Cl2 at 26 ˚C.CompoundΔH˚f (J/mol K)ΔS˚f (J/mol K)C2H4Cl2(g)–129.7308.0C2H4Br2(g)38.3330.6C2H4I2(g)66.5347.8
Ethene (C2H4) can be halogenated by the following reaction: C2H4(g) + X2(g) ⇌ C2H4X2(g), where X2 can be Cl2, Br2, or I2.Use the thermodynamic data given below to calculate ΔS˚ for the halogenation reaction by Br2 at 26 ˚C.CompoundΔH˚f (J/mol K)ΔS˚f (J/mol K)C2H4Cl2(g)–129.7308.0C2H4Br2(g)38.3330.6C2H4I2(g)66.5347.8
Ethene (C2H4) can be halogenated by the following reaction: C2H4(g) + X2(g) ⇌ C2H4X2(g), where X2 can be Cl2, Br2, or I2.Use the thermodynamic data given below to calculate ΔS˚ for the halogenation reaction by I2 at 26 ˚C.CompoundΔH˚f (J/mol K)ΔS˚f (J/mol K)C2H4Cl2(g)–129.7308.0C2H4Br2(g)38.3330.6C2H4I2(g)66.5347.8
Calculate ΔS°298 for the following change.(a) SnCl4(l) ⟶ SnCl4(g)
Calculate ΔS°298 for the following change.(b) CS2(g) ⟶ CS2(l)
Calculate ΔS°298 for the following change.(c) Cu(s) ⟶ Cu(g)
Calculate ΔS°298 for the following change.(d) H2O(l) ⟶ H2O(g)
Calculate ΔS°298 for the following change.(e) 2H2(g) + O2(g) ⟶ 2H2O(l)
Calculate ΔS°298 for the following change.(f) 2HCl(g) + Pb(s) ⟶ PbCl 2(s) + H2(g)
H2 reacts with the halogens (X2) according to the following reaction: H2(g) + X2(g) ⇌ 2 HX(g), where X2 can be Cl2, Br2, or I2.Reactant/ProductΔH˚f (kJ/mol)ΔS˚f (J/mol K) H2(g)0130.7Cl2(g)0223.1HCl(g)–92.3186.9Br2(g)30.9245.5HBr(g)–36.3198.7I2(g)62.42260.69HI(g)26.5206.6Calculate ΔS˚ for the reaction between hydrogen and Cl2{ m Cl_2}.
Calculate ΔS°298 for the following change.(g) Zn(s) + CuSO4(s) ⟶ Cu(s) + ZnSO4(s)
Determine the entropy change for the combustion of liquid ethanol, C 2H5OH, under the standard conditions to give gaseous carbon dioxide and liquid water.
Determine the entropy change for the combustion of gaseous propane, C 3H8, under the standard conditions to give gaseous carbon dioxide and water.
H2 reacts with the halogens (X2) according to the following reaction: H2(g) + X2(g) ⇌ 2 HX(g), where X2 can be Cl2, Br2, or I2.Reactant/ProductΔH˚f (kJ/mol)ΔS˚f (J/mol K) H2(g)0130.7Cl2(g)0223.1HCl(g)–92.3186.9Br2(g)30.9245.5HBr(g)–36.3198.7I2(g)62.42260.69HI(g)26.5206.6Calculate ΔS˚ for the reaction between hydrogen and Br2.
Using the relevant S°298 values listed in Appendix G, calculate ΔS°298 for the following change:(a) N2(g) + 3H2(g) ⟶ 2NH3(g)
Using the relevant S°298 values listed in Appendix G, calculate ΔS°298 for the following change:(b) N2(g) + 5/2O2(g) ⟶ N2O5(g)
From the following information, determine ΔS°298 for the following:N(g) + O(g)⟶NO(g)                ΔS° 298 = ?N2(g) + O2(g)⟶2NO(g)          ΔS° 298 = 24.8 J/KN2(g)⟶2N(g)                           ΔS°  298 = 115.0 J/KO2(g)⟶2O(g)                          ΔS°  298 = 117.0 J/K
H2 reacts with the halogens (X2) according to the following reaction: H2(g) + X2(g) ⇌ 2 HX(g), where X2 can be Cl2, Br2, or I2.Reactant/ProductΔH˚f (kJ/mol)ΔS˚f (J/mol K) H2(g)0130.7Cl2(g)0223.1HCl(g)–92.3186.9Br2(g)30.9245.5HBr(g)–36.3198.7I2(g)62.42260.69HI(g)26.5206.6Calculate ΔS˚ for the reaction between hydrogen and I2.
Use the standard entropy data in Appendix G to determine the change in entropy for each of the reactions listed below. All the processes occur at the standard conditions and 25 °C.(a) MnO2(s) ⟶ Mn(s) + O2(g)(b) H2(g) + Br2(l) ⟶ 2HBr(g)(c) Cu(s) + S(g) ⟶ CuS(s)(d) 2LiOH(s) + CO2(g) ⟶ Li2CO3(s) + H2O(g)(e) CH4(g) + O2(g) ⟶ C(s, graphite) + 2H 2O(g)(f) CS2(g) + 3Cl2(g) ⟶ CCl4(g) + S2Cl2(g)
Use the standard entropy data in Appendix G to determine the change in entropy for each of the reactions listed below. All the processes occur at the standard conditions and 25 °C.(a) C(s, graphite) + O2(g) ⟶ CO2(g)(b) O2(g) + N2(g) ⟶ 2NO(g)(c) 2Cu(s) + S(g) ⟶ Cu2 S(s)(d) CaO(s) + H2 O(l) ⟶ Ca(OH)2(s)(e) Fe2 O3(s) + 3CO(g) ⟶ 2Fe(s) + 3CO2(g)(f) CaSO4 ·2H2 O(s) ⟶ CaSO4(s) + 2H2 O(g)
In photosynthesis, plants form glucose (C6H12O6) and oxygen from carbon dioxide and water. Calculate ΔS˚rxn at 15 ˚C{ m ^circ~ m C}.
Consider the following reaction:   2NOBr(g) ⥫⥬ 2NO(g) + Br 2(g)      K = 0.42 at 373 KGiven that S° of NOBr(g) = 272.6 J/mol·K and that ΔS°rxn and ΔH°rxn are constant with temperature, find(a) ΔS°rxn at 298 K 
Propylene (propene; CH3CH=CH2) is used to produce polypropylene and many other chemicals. Although most propylene is obtained from the cracking of petroleum, about 2% is produced by catalytic dehydrogenation of propane (CH3CH2CH3): Because this reaction is endothermic, heaters are placed between the reactor vessels to maintain the required temperature.(a) If the molar entropy, S°, of propylene is 267•1 J/mol•K, find its entropy of formation, S  fo
Calculate ΔS˚rxn for the balanced chemical equation2 H2S(g) + 3 O2(g)  →  2 H2O(g) + 2 SO2(g)Standard enthalpies for selected substances at 25oC SubstanceΔS˚ (J/(mol•K))O2(g)205.2SO2(g)248.2SO3(g)256.8H2O(g)188.8H2S(g)205.8
The heat of vaporization of methanol, CH3OH, is 35.2 kJ/mol. Its boiling point is 64.6°C. What is the change in entropy for the vaporization of methanol?
Use standard entropies to calculate ΔS˚rxn for the balanced chemical equation: 2 PCl3(l) + O2(g) →  2 POCl3(l)SubstanceΔS˚ (J/mol•K)POCl3(l)222.5POCl3(g)325.5PCl3(l)217.1PCl3(g)311.8O2(g)205.2
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.a. 2H2S (g) + SO2 (g) → 3Srhombic (s) + 2H2O (g)
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.b. 2SO3 (g) → 2SO2 (g) + O2 (g)
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.c. Fe2O3 (s) + 3H2 (g) → 2Fe (s) + 3H 2O (g)
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.a. H2 (g) + 1/2O2 (g) → H2O (l)
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.b. 2CH3OH (g) + 3O2 (g) → 2CO2 (g) + 4H2O (g)
Predict the sign of ΔS° and then calculate ΔS° for each of the following reactions.c. HCl (g) → H+ (aq) + Cl - (aq)
For the reactionC2H2 (g) + 4F2 (g) → 2CF4 (g) + H2 (g)ΔS° is equal to -358 J/K. Use this value and data from Appendix 4 to calculate the value of S° for CF4(g).
For the reactionCS2 (g) + 3O2 (g) → CO2 (g) + 2SO2 (g)ΔS° is equal to -143 J/K. Use this value and data from Appendix 4 to calculate the value of S° for CS2(g).
For the following reaction, predict the sign and find the value of ΔS°rxn:(a) 3NO(g) ⟶ N2O(g) + NO2(g)
For the following reaction, predict the sign and find the value of ΔS°rxn:(b) 3H2(g) + Fe2O3(s) ⟶ 2Fe(s) + 3H 2O(g)
For the following reaction, predict the sign and find the value of ΔS°rxn:(c) P4(s) + 5O2(g) ⟶ P4O10(s)
For the following reaction, predict the sign and find the value of ΔS°rxn:(a) 3NO2(g) + H2O(l) ⟶ 2HNO3(l) + NO(g)
For the following reaction, predict the sign and find the value of ΔS°rxn:(b) N2(g) + 3F2(g) ⟶ 2NF3(g)
For the following reaction, predict the sign and find the value of ΔS°rxn:(c) C6H12O6(s) + 6O2(g) ⟶ 6CO2(g) + 6H2O(g)
Find ΔS°rxn for the combustion of ethane (C2H6) to carbon dioxide and gaseous water. Is the sign of ΔS°rxn as expected?
Find ΔS°rxn for the reaction of nitrogen monoxide with hydrogen to form ammonia and water vapor. Is the sign of ΔS°rxn as expected?
Find ΔS°rxn for the combustion of ammonia to nitrogen dioxide and water vapor. Is the sign of ΔS°rxn as expected?
Find ΔS°rxn for the formation of Cu 2O(s) from its elements.
Find ΔS°rxn for the formation of HI(g) from its elements.
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.C2H4(g) + H2(g) → C2H6(g)
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.C(s) + H2O(g) → CO(g) + H2(g)
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.CO(g) + H2O(g) → H2(g) + CO2(g)
Use data from Appendix IIB in the textbook to calculate ΔS˚rxn for each of the following reactions.2 H2S(g) + 3 O2(g) → 2 H2O(l) + 2 SO2(g)
Use data from Appendix IIB to calculate ΔS˚rxn for each of the reactions given below.3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)
Use data from Appendix IIB to calculate ΔS˚rxn for each of the reactions given below.Cr2O3(s) + 3 CO(g) → 2 Cr(s) + 3 CO2(g)
Find ΔS°rxn for the formation of CH3OH(l) from its elements.
Use data from Appendix IIB to calculate ΔS˚rxn for each of the reactions given below.N2O4(g) + 4 H2(g) → N2(g) + 4 H2O(g)
Find ΔS°rxn for the formation of N2O(g) from its elements.
Find ΔS˚ for the formation of CH3Cl(g) { m CH}_3{ m Cl}(g) from its elements in their standard states.
Sulfur dioxide is released in the combustion of coal. Scrubbers use aqueous slurries of calcium hydroxide to remove the SO2 from flue gases. Write a balanced equation for this reaction and calculate ΔS°rxn at 298 K [S° of CaSO3(s) = 101.4 J/mol·K].
Oxyacetylene welding is used to repair metal structures, including bridges, buildings, and even the Statue of Liberty. Calculate ΔS°rxn for the combustion of 1 mol of acetylene (C 2H2).
Find ΔS˚ for the reaction between nitrogen gas and fluorine gas to form nitrogen trifluoride gas.large{frac{1}{2} m N_2(g);+;frac{3}{2}F_2(g); ightarrow;NF_3(g)}
Consider the following reaction:H2O(g) + Cl 2O(g) → 2HOCl(g)     K 298 = 0.090For Cl2O(g),       ΔG°f = 97.9 kJ/mol       ΔH°f = 80.3 kJ/mol           S° = 266.1 J/K • mold. Estimate ΔH°f and S° for HOCl(g).
Methanol burns in oxygen to form carbon dioxide and water. Calculate ΔS˚rxn at 25 ˚C.
For the gaseous reaction of xenon and fluorine to form xenon hexafluoride:(a) Calculate ΔS° at 298 K (ΔH° = −402 kJ/mol and ΔG° = −280. kJ/mol).
For the gaseous reaction of carbon monoxide and chlorine to form phosgene (COCl  2):(a) Calculate ΔS° at 298 K (ΔH° = −220. kJ/mol and ΔG° = −206 kJ/mol).
“Thermite” reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite reaction is Fe2 O3(s) + 2Al(s) ⟶ Al2 O3(s) + 2Fe(s). Is the reaction spontaneous at room temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol of heat.
By calculating ΔSuniv at each temperature, determine if the melting of 1 mole of NaCl(s) is spontaneous at 500 °C and at 700 °C.What assumptions are made about the thermodynamic information (entropy and enthalpy values) used to solve this problem?
A reaction has H˚rxn = –127 kJ and S˚rxn = 316 J/K. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings?
What is the change in entropy when 0.200 mol of potassium freezes at 63.7°C (ΔH  fus = 2.39 kJ/mol)?
Calculate ΔSsurr for the following reactions at 25°C and 1 atm.a. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)     ΔH° = -2221 kJ
Calculate ΔSsurr for the following reactions at 25°C and 1 atm.b. 2NO2(g) → 2NO(g) + O2(g)              ΔH° = 112 kJ
Determine the normal boiling point (in kelvin) of dichloroethane, CH 2Cl2. Find the actual boiling point using the Internet or some other source, and calculate the percent error in the temperature. Explain the differences, if any, between the two values.
Ethanethiol (C2H5SH; also called ethyl mercaptan) is commonly added to natural gas to provide the “rotten egg” smell of a gas leak. The boiling point of ethanethiol is 35°C and its heat of vaporization is 27.5 kJ/mol. What is the entropy of vaporization for this substance?
For mercury, the enthalpy of vaporization is 58.51 kJ/mol and the entropy of vaporization is 92.92 J/K•mol. What is the normal boiling point of mercury?
Given the data, calculate ΔSvap for each liquids. (ΔSvap = ΔHvap/T, where T is in K)CompoundNameBP (oC)ΔHvap (kJ/mol) at BPC4H10ODiethyl ether34.626.5C3H6OAcetone56.129.1C6H6Benzene79.830.8CHCl3Chloroform60.829.4C2H5OHEthanol77.838.6H2OWater10040.7
For ammonia (NH3), the enthalpy of fusion is 5.65 kJ/mol and the entropy of fusion is 28.9 J/K•mol.b. What is the approximate melting point of ammonia?
The enthalpy of vaporization of ethanol is 38.7 kJ/mol at its boiling point (78°C). Determine ΔSsys, ΔSsurr, and ΔSuniv when 1.00 mole of ethanol is vaporized at 78°C and 1.00 atm.
A reaction has Hrxn = –124kJ and Srxn = 276J/K. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings?
For rubidium ΔH°vap = 69.0 kJ/mol at 686°C, its boiling point. Calculate ΔS°, q, w, and ΔE for the vaporization of 1.00 mole of rubidium at 686°C and 1.00 atm pressure.
For a certain reaction ΔHrxn= –54.9 kJ. Calculate the change in entropy for the surroundings (ΔSsurr) for the reaction at 31 ˚C. (Assume constant pressure and temperature.)
Given the thermodynamic data below, calculate ΔS and ΔS surr for the following reaction at 25°C and 1 atm:                       XeF  6(g) →XeF4(s) + F2(g)
Consider the reaction between nitrogen and oxygen gas to form dinitrogen monoxide: 2 N2(g) + O2(g)  →  2 N2O(g), ΔHrxn = + 163.2 kJCalculate the entropy change in the surroundings associated with this reaction occurring at 25 ˚C.
Calculate the change in entropy that occurs in the system when 3.10 mole of isopropyl alcohol (C3H8O) melts at its melting point (-89.5 ˚C). ΔHfus = 5.37 kJ/mol
Calculate the change in entropy that occurs in the system when 3.10 mole of diethyl ether (C4H6O) condenses from a gas to a liquid at its normal boiling point (34.6 ˚C). ΔHvap = 26.5 kJ/mol
Calculate the change in entropy that occurs in the system when 45.0 g of acetone (C3H6O) freezes at its melting point (-94.8 ˚C). ΔHfus = 5.69 kJ/mol.
Calculate the change in entropy that occurs in the system when 55.0 g of water vaporizes from a liquid to a gas at its boiling point (100.0 ˚C). ΔHvap = 40.7 kJ/mol
Calculate ΔSsurr at the indicated temperature for a reaction.ΔH˚rxn = –279 kJ; 298 K
Calculate ΔSsurr at the indicated temperature for a reaction.ΔH˚rxn = –279 kJ; 73 K
Calculate ΔSsurr at the indicated temperature for a reaction.ΔH˚rxn = 128 kJ; 298 K
Calculate ΔSsurr at the indicated temperature for a reaction.ΔH˚rxn = 128 kJ; 73 K
Calculate ΔSuniv for the formation of Cu2O(s) from its elements, and state whether the reaction is spontaneous at 298 K.
Calculate ΔSuniv for the formation of HI(g) from its elements, and state whether the reaction is spontaneous at 298 K.
If the normal boiling point of a liquid is 67 oC, and the standard molar entropy change for the boiling process is +100 J/K, estimate the standard molar enthalpy change for the boiling process.
Calculate the boiling point of benzene, C6H6 from the data given below:C6H6 (l) → C6H6 (g)  
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ: ΔH˚rxn = 126 kJ , ΔS˚rxn = –254 J/K, T = 301 K.
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ: ΔH˚rxn = –126 kJ , ΔS˚rxn = 254 J/K, T = 301 K.
Calculate the change in entropy that occurs in the system when 1.50 mol of methanol (CH3OH) vaporizes from a liquid to a gas at its boiling point (64.6 ˚C).For methanol, ΔHvap = 35.21 kJ/mol.
Calculate ΔSuniv for the formation of CH3OH(l) from its elements, and state whether the reaction is spontaneous at 298 K.
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ: ΔH˚rxn = –126 kJ , ΔS˚rxn = –254 J/K, T = 301 K.
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ: ΔH˚rxn = –126 kJ , ΔS˚rxn = –254 J/K, T = 556 K.
Calculate ΔSuniv for the formation of N2O(g) from its elements, and state whether the reaction is spontaneous at 298 K.
Calculate the entropy change for the vaporization of liquid methane and liquid hexane using the following data.Compare the molar volume of gaseous methane at 112 K with that of gaseous hexane at 342 K. How do the differences in molar volume affect the values of ΔSvap for these liquids?
Given the values of ΔH˚rxn, ΔS˚rxn, and T, Delta S_{ m rxn}^circdetermine ΔS˚univDelta S_{{ m{univ}}}.ΔH˚rxn = –86 kJ, ΔS˚rxn = –148 J/K, T = 301 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ.ΔH˚rxn = –86 kJ, ΔS˚rxn = –148 J/K, T = 758 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ.ΔH˚rxn = +86 kJ, ΔS˚rxn = –148 J/K, T = 301 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ.ΔH˚rxn = –86 kJ, ΔS˚rxn = +148 J/K, T = 401 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ. Predict whether or not the reaction will be spontaneous. (Assume that all reactants and products are in their standard states.)ΔH˚rxn = –95 kJ; ΔS˚rxn = –157 J/K; T = 298 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ. Predict whether or not the reaction will be spontaneous. (Assume that all reactants and products are in their standard states.)ΔH˚rxn = –95 kJ; ΔS˚rxn = –157 J/K; T = 855 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ. Predict whether or not the reaction will be spontaneous. (Assume that all reactants and products are in their standard states.)ΔH˚rxn = +95 kJ; ΔS˚rxn = –157 J/K; T = 298 K
Given the values of ΔH˚rxn, ΔS˚rxn, and T, determine ΔS˚univ. Predict whether or not the reaction will be spontaneous. (Assume that all reactants and products are in their standard states.)ΔH˚rxn = –95 kJ; ΔS˚rxn = +157 J/K; T = 398 K
Iron melts at 1535°C and its enthalpy of fusion is 13.8 kJ/mol. Calculate the entropy of fusion per mole of iron.
Calculate the entropy change for the vaporization of 25.0 g of hexane, C  6H14, at its boiling point of 68.8°C. The enthalpy of vaporization of hexane is 28.8 kJ/mol.
Calculate the entropy change of a 235 g sample of copper that is heated at constant pressure from 32.0°C to 125°C. CP,m for copper = 24.5 J/mol•K.
The temperature of a 625 g piece of granite is increased from 18.0°C to 60.0°C. What is its change in entropy? The specific heat capacity of granite is 0.790 J/g•K.
The boiling point of chloroform, CHCl 3, is 61.2°C. Use Trouton’s rule to estimate the enthalpy of vaporization of chloroform.
Calculate the change in entropy that occurs in the system when 30.5 g of acetone (C3H6O) vaporizes from a liquid to a gas at its normal boiling point (56.1 ˚C).
Given the values of ΔHºrxn, ΔSºrxn, and T below determine ΔSuniv.ΔHºrxn = -81 kJ,ΔSrxn = -149 J/K,T = 301 ºKExpress your answer using two significant figures.
Consider the following reaction at 298 ºK: C(graphite) + 2Cl2(g)→CCl4(l) Δ H = -139 kJ Calculate the following quantities. Find standard entropy values here in J/K.a) ΔSsysb) ΔSsurrc) ΔSuniv
The normal boiling point of ethanol (C2H5OH) is 78.3 ° C and its molar enthalpy of vaporization it 38.56 kJ/mol. What is the change in entropy of the system in J/K when 77.2 grams of ethanol at 1 atm condenses to a liquid at the normal boiling point?a) 825b) -825c) -263d) -184e) 263
A 15 g piece of metal (138.4 g/mol) melts at 1774 °C and its enthalpy of fusion is 17.4/mol. Calculate the entropy of fusion (J/K) of the metal. Enter to 2 decimal places.
Consider the reaction: I2 (g) + Cl2 (g) → 2ICl (g) Using standard absolute entropies at 298K, calculate the entropy change for the system when 2.49 moles of I2 (g) react at standard conditions. ΔS° system =                            J/K
The temperature of a 874 g piece of granite is increased from 19.2°C to 69.2°C. What is its change in entropy J/K)? The specific heat capacity of granite is 0.790 J/g • K.
The ΔHvapo of a certain compound is 13.08 kJ mol-1 and its ΔSvapo is 67.74 J mol-1 K-1.What is the normal boiling point of this compound?
Using the data in the table, calculate the standard entropy changes (J/mol•K) for the following reactions at 25 °C.S(s) + O2(g) → SO2(g)MgCO3(s) → MgO(s) + CO2(g)2 C2H6(g) + 7O2(g) → 4 CO2(g) + 6 H2O(l)
Calculate the standard entropy change for the following reaction at 25 °C. S° values can be found here.C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g)
Nitric oxides, NO and NO2, contribute to air pollution, acid rain, and the depletion of the ozone layer. After NO forms in the combustion chamber of an automobile engine, it reacts further with oxygen to form NO2. The reaction is given by2NO (g) + O2 (g) → 2NO2 (g) The following table gives some entropy values: Part ACalculate ΔS°rxn for the reaction 2NO (g) + O2 (g) → 2NO2 (g) Express your answer to one decimal place and include the appropriate units. Part BA negative change in entropy indicates that (i) the products are more disordered than the reactants (ii) the products are less disordered than the reactants
Consider the reaction:3 Fe2O3 (s) + H2 (g) → 2Fe3O4 (s) + H2O(g)Using standard absolute entropies at 298K, calculate the entropy change for the system when 2.29 moles of Fe2O3(s) react at standard conditions. ΔSº system = _____J/K
Entropy of Reaction for Nitrogen Dioxide Formation Nitric oxides. NO and NO2, contribute to air pollution, acid rain, and the depletion of the ozone layer. After NO forms in the combustion chamber of an automobile engine, it reacts further with oxygen to form NO2. The reaction is given by 2NO (g) + O2 (g) → 2NO2 (g) The following table gives some entropy values: Part ACalculate ΔS°rxn for the reaction 2NO (g) + O2 (g) → 2NO2 (g)
Calculate the standard entropy change for the following reaction, 2SO2 (g) + O2 (g) → 2SO3 (g) given S° [SO2 (g)] = 248.2 J/K • mol. S° [O2 (g)] = 205. 1 J/K • mol, and S° [SO3 (g)] = 256.8 J/K • mol. (a) -196.5 J/K • mol-rxn (b) -94.0 J/K • mol-rxn (c) -187.9 J/K • mol-rxn (d) +187.9 J/K • mol-rxn (e) +196.5 J/K • mol-rxn
Using the following data, calculate ΔSfus (J•K -1•mol -1) and  ΔSvap (J•K -1•mol -1) for Na.
The ΔHvap of a certain compound is 28.26 kJ mol and its ΔSvap is 50.01 J•mol-1•K-1. What is the boiling point of this compound?
Suppose a heat source generates heat at a rate of 54.0 W (1 W = 1 J/s). How much entropy does this produce per hour in the surroundings at 25.0 °C? Assume the heat transfer is reversible.
Given the hypothetical reaction. 4 X(s) + 6Y(s) → 4Z (s) + 9A(g) Calculate Δ S for this reaction at 25°C, given the following absolute entropies: S°J/(K-mol) X (s) 40.72 Y(s) 28.64 Z(s) 66.92 A(g) 54.98
Part BCalculate the standard entropy change for the reaction P4 (g) + 5O2 (g) → P4O10 (s) using the data from the following table: Express your answer in joules per kelvin using four significant figures.
Calculate the standard entropy change for the following reaction at 25°C.2CH3OH(g) + 3O2(g) → 2CO2(g) + 4H2O(g)
Use the data from this table of thermodynamic properties to calculate the values of delta S°rxn for each of the following reactions at 25 °C. (a) 4NH3 (g) + 7O2 (g) → 4NO2 (g) + 6H2O (g)      (b) N2 (g) + O2 (g) → 2NO (g) 
Calculate ΔS° compositefunction (in J/mol • K) for the following reaction. 2HCl (g) + Pb (s) → PbCl2 (s) + H2 (g)
Using the following data, calculate ΔSfus and ΔSvap for Cs. 
The ΔHvap of a certain compound is 48.17 kJ mol-1 and its ΔSvap is 52.91 J mol-1•K-1. What is the boiling point of this compound?
Which of the following processes shows a decrease in entropy of the system? NaClO3 (s) → Na+ (aq) ClO3- (aq) CH3OH (l) → CO (g) + 2H 2 (g) H2O(l) → H2O (g) 2NO (g) + O2 (g) → 2NO2 (g) COCl2 (g) → CO (g) + Cl 2 (g) 
Use the data from this table of thermodynamic properties to calculate the values of ΔS°rxn for each of the following reactions at 25° C. 2CO(g) + O2(g) → 2CO2(g)
A reaction had ΔH°rxn = - 130 kJ and ΔS°rxn = 316 J/K. Part AAt what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings? Express your answer in kelvins. 
Calculate the standard entropy change for the following reaction at 25 °C. S° values can be found here. HCl (g) + NaOH (s) → NaCl (s) + H2O (l) 
Calculate the standard entropy change for the following reaction at 25°C. S° values can be found here.HCl(g)+ NaOH(s) → NaCl(s) + H2O(l)
Calculate the standard entropy change for the following reaction at 25°C. S° values can be found here. Mg(OH)2 (s) + 2HCl (g) → MgCl2 (s) + 2H2O (g) 
Identify the process in which the entropy increases.a. the phase transition from a solid to a gasb. the phase transition from a gas to a solidc. the phase transition from a gas to a liquidd. the phase transition from a liquid to a solide. a decrease in the number of moles of a gas during a chemical reaction 
The entropy of 0.002 mole of CH2CI2 (aq) is greater than the entropy of 0.002 mole of CH2CI2 (l).a. Trueb. False
Entropy is a measure of a. free energy. b. the heat of a reaction. c. the rate of a reaction. d. molecular randomness. 
The entropy of 0.5 mole LiBr (s) at 290 K is greater than the entropy of 0.5 mole LiBr (s) at 330Ka. Trueb. False 
Place the following in order of increasing standard molar entropy.H2O(l) H2O(g) H2O(s) a. H2O(g), H2O(s), H2O(l) b. H2O(l), H2O(s), H2O(g) c. H2O(g), H2O(l), H2O(s) d. H2O(s), H2O(l), H2O(g) 
Which provides the greatest decrease in entropy?
Sodium reacts violently with water according to the equation: 2 Na(s) + 2 H2O(l) →2NaOH(aq) + H2(g) The resulting solution has a higher temperature than the water prior to the addition of sodium. What are the signs of ΔH°and ΔS° for this reaction?a. ΔH° is negative and ΔS° is positive.b. ΔH° is positive and ΔS° is negative. c. ΔH° is negative and ΔS° is negative. d, ΔH° is positive and ΔS° is positive. 
The entropy of 1 mole of N2 (g) is greater than the entropy of 1 mole of N2(aq).a. Trueb. False 
Consider the following reaction at 298 K:2C (graphite) + O2 (g) → 2CO (g)  Delta H = -110.5 kJCalculate:Delta S(sys) J/KDelta S (surr) J/KDelta S (Univ) J/K
A favorable entropy change occurs when ΔS is positive. What can be said about the order of the system when ΔS is positive.a) system order increasesb) system order stays the samec) system disorder increases
Predict the sign of the entropy change, ΔS°, for the following reaction.Pb2+ (aq) + 2Cl− (aq) → PbCl2(s)a) Negativeb) Positive                                                   
Predict how the entropy of the substance is affected in the following processes:
Calculate ΔS°rxn for the following reaction:4Cr(s) + 3O2(g) → 2Cr2O3(s).Substance            ΔS°, J/K·molCr(s)                        23.77O2(g)                       205.138Cr2O3(s)                  81.2a. 548.1 J/Kb. 147.7 J/Kc. -147.7 J/Kd. -548.1 J/K
Select the molecule with the highest gas-phase absolute entropy at 25 ºC. a) CH4 b) C4H10 c) C3H8 d) C2H6
Which of the following would have the highest entropy assuming one mole of each substance and the same temperature for each. a) HBr(g) b) H2(g) c) HBrO4 d) He(g)
Without referring to a data table, rank the following compounds by standard molar entropy.i) CH3OH (g)ii) O2 (g)iii) N2 (g) 
Consider the following reaction at 298 K:2 H2 (g) + O2 (g) → 2 H2O (g)     ΔH= -483.6 KJCalculate the following quantities.i) ΔSsys=ii) ΔSsurr=iii) ΔSuniv=
Which of the following is true for an endothermic process?a. qsys > 0, ΔSsurr < 0b. qsys < 0, ΔSsurr > 0c. qsys < 0, ΔSsurr < 0d. qsys > 0, ΔSsurr > 0
Rank these systems in order of decreasing entropy.Rank from highest to lowest entropy. To rank items as equivalent, overlap them.i) 1 mol of oxygen gas at 273 K and 40 Lii) 1/2 mol of xenon gas at 100 K and 20 Liii) 1 mol of xenon gas at 273 K and 20 Liv) 1/2 mol of liquid xenon at 100 Kv) 1 mol of xenon gas at 273 K and 40 Lvi) 1 mol of carbon tetrachloride gas at 273 K and 40 Lvii) 1/2 mol of xenon gas at 273 K and 20 L
Which of the following reactions have a positive ΔSrxn? Check all that apply.A. A(g) + B(g) → 3 C(g)B. A(g) + B(s) → C(g)C. A(g) + B(g) → C(g)D. A(g) + 2 B(g) → C(g)
Calculate the standard entropy change for the following reaction at 25°C.MgCl2(s) + H2O(l) → MgO(s )+ 2HCl(g)