Ch.6 - Thermochemistry WorksheetSee all chapters
All Chapters
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
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
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

A thermochemical equation is a stoichiometric question that now involves the variable of ΔHReaction. Instead of doing a mole to mole comparison we will now do a mole to ΔH comparison. 

Enthalpy and Chemical Reactions

Concept #1: Understanding Thermochemical Equations

Example #1: Iron is reacts with oxygen according to the following equation at around 2000oC.  (0:35 – 4:10)

4 Fe (s)  +  3 O­2 (g)  → 2 Fe2O3 (s)         

ΔHo = + 65.2 kJ/mol

Calculate the amount of grams of iron (III) oxide, Fe2O3, produced from the absorption of 4.82 x 109 J. 

Practice: Nitromethane (CH3NO2), sometimes used as a fuel for drag racing, burns according to the following reaction: 4 CH3NO2 (l) + 7 O2 (g) -----> 4 CO2 (g) + 6 H2O (g) + 4 NO2 (g) ?H = ? 2441.6 kJ How much heat is released by burning 125.0 g of nitromethane (MW: 61.044 g/mol)?

Additional Problems
Given the chemical reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g)                 ΔH = −2044 kJ How much energy would be released if 2.0 moles of O 2 were reacted? A. 8.2 * 10 2 kJ B. 2.1 * 10 3 kJ C. 4.1 * 10 3 kJ D. 2.0 * 10 4 kJ E. 1.3 * 10 5 kJ
What mass and volume of benzene (C6H6, d= 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 3.3 x 108 kJ of heat according to the following reaction? 2 C6H6 (l) + 15 O 2 (g)   →   12 CO 2 (g) + 6 H2O (g)          ΔH°rxn = – 6278 kJ  
Consider the process of 2 H(g) → H2(g) where ΔH = −436 kJ/mol Determine if the sentence below is true or false. Reacting two moles of H(g) would produce 2.02 grams of H2
Determine the amount of heat (in kJ) given off when 1.26 x 10 4 g of NO2 are produced according to the equation: 2NO(g) + O2(g) → 2NO2(g)            ΔHRXN = -114.6 kJ/mol
A large part of the driving force in a thermite reaction is based on the stability of aluminum oxide, as reflected in ΔH° of the following reaction: 2Al (s) + 3/2 O2 (g) → Al2O3 (s) ΔH° =  - 1669.8 kJ/mol   If 27 g of aluminum reacts with oxygen to form Al 2O3(s), how much heat is released assuming the reaction goes to completion?
Calculate the amount of heat (kJ) released in the complete combustion of 8.17 g of Al to form aluminum oxide at 25°C and under a pressure of 1 atm. The ∆H for aluminum oxide = -1676 kJ/mol. 4 Al   +   3 O2   →   2 Al2O3
What mass of water would need to evaporate from your skin in order to dissipate 1.7 x 105 J of heat from your body? H2O(l) → H2O(g)           ΔH vap = 40.7 kJ/mol   A) 7.52 x 104 g B) 418 g C) 75.2 g D) 58.4 g E) 6.92 x 106 g
Given the chemical reaction: C + 2 H 2 → CH4 has a ΔH = −74.9 kJ how much energy in kJ changes if 35.0 g of H2 is reacted? A) −218         B) −649           C) −1.30 x 103           D) −2620           E) −5240  
The standard enthalpies of formation of gaseous propyne (C3H4), propylene (C3H6), and propane (C3H8) are +185.4, +20.4, and -103.8 kJ/mol, respectively.Calculate the heat evolved per mole on combustion of each substance to yield CO2(g) and H2O(g).
The standard enthalpies of formation of gaseous propyne (C3H4), propylene (C3H6), and propane (C3H8) are +185.4, +20.4, and -103.8 kJ/mol, respectively.Calculate the heat evolved on combustion of 6 kg of each substance.
The heat of combustion of fructose, C6 H12 O6, is -2812 kJ/mol.If a fresh golden delicious apple weighing 4.26 oz (121 g ) contains 17.0 g of fructose, what caloric content does the fructose contribute to the apple?
Consider two solutions, the first being 50.0 mL of 1.00 M CuSO4 and the second 50.0 mL of 2.00 M KOH. When the two solutions are mixed in a constant-pressure calorimeter, a precipitate forms and the temperature of the mixture rises from 21.5 oC to 27.7 oC.From the calorimetric data, calculate H for the reaction that occurs on mixing. Assume that the calorimeter absorbs only a negligible quantity of heat, that the total volume of the solution is 100.0 mL, and that the specific heat and density of the solution after mixing are the same as that of pure water.
Consider the following reaction: 2Mg(s) + O2 (g) → 2MgO(s) H = - 1204How many kilojoules of heat are absorbed when 40.5 g of MgO(s) is decomposed into Mg(s) and O2 (g) at constant pressure?
A 2.250 -g sample of quinone (C6 H4 O2 ) is burned in a bomb calorimeter whose total heat capacity is 7.854kJ/oC. The temperature of the calorimeter increases from 22.96 oC to 30.25 oC.What is the heat of combustion per gram of quinone?
A 2.250 -g sample of quinone (C6 H4 O2 ) is burned in a bomb calorimeter whose total heat capacity is 7.854kJ/oC. The temperature of the calorimeter increases from 22.96 oC to 30.25 oC.What is the heat of combustion per mole of quinone?
A 1.800-g sample of solid phenol (C6H5OH(s)) was burned in a bomb calorimeter, which has a total heat capacity of 11.66 kJ/oC. The temperature of the calorimeter plus its contents increased from 21.36oC to 26.37oC. You may want to reference (Pages 178 - 183)Section 5.5 while completing this problem.What is the heat of combustion per gram of phenol?
Under constant-volume conditions the heat of combustion of glucose (C6H12O6) is 15.57 kJ/g. A 3.550 -g sample of glucose is burned in a bomb calorimeter. The temperature of the calorimeter increased from 20.95 oC to 24.75 oC.What is the total heat capacity of the calorimeter?
Under constant-volume conditions the heat of combustion of glucose (C6H12O6) is 15.57 kJ/g. A 3.550 -g sample of glucose is burned in a bomb calorimeter. The temperature of the calorimeter increased from 20.95 oC to 24.75 oC.If the size of the glucose sample had been exactly twice as large, what would the temperature change of the calorimeter have been?
Under constant-volume conditions the heat of combustion of benzoic acid (C6H5COOH) is 26.38 kJ/g. A 2.760 -g sample of benzoic acid is burned in a bomb calorimeter. The temperature of the calorimeter increases from 21.50 oC to 29.95 oC.What is the total heat capacity of the calorimeter?
Ethanol (C2H5OH) is currently blended with gasoline as an automobile fuel.Calculate the heat produced per liter of ethanol by combustion of ethanol under constant pressure. Ethanol has a density of 0.789 g/mL.
The automobile fuel called E85 consists of 85% ethanol and 15% gasoline. E85 can be used in so-called flex-fuel vehicles (FFVs), which can use gasoline, ethanol, or a mix as fuels. Assume that gasoline consists of a mixture of octanes (different isomers of C8H18), that the average heat of combustion of C8H18(l) is 5400 kJ/mol, and that gasoline has an average density of 0.70 g/mL. The density of ethanol is 0.79 g/mL.By using the information given, calculate the energy produced by combustion of 3.0 L of gasoline.
The automobile fuel called E85 consists of 85% ethanol and 15% gasoline. E85 can be used in so-called flex-fuel vehicles (FFVs), which can use gasoline, ethanol, or a mix as fuels. Assume that gasoline consists of a mixture of octanes (different isomers of C8H18), that the average heat of combustion of C8H18(l) is 5400 kJ/mol, and that gasoline has an average density of 0.70 g/mL. The density of ethanol is 0.79 g/mL.By using the information given as well as data in Appendix C, calculate the energy produced by combustion of 3.0 L of ethanol. Consider that water is in the gaseous state.
The automobile fuel called E85 consists of 85% ethanol and 15% gasoline. E85 can be used in so-called flex-fuel vehicles (FFVs), which can use gasoline, ethanol, or a mix as fuels. Assume that gasoline consists of a mixture of octanes (different isomers of C8H18), that the average heat of combustion of C8H18(l) is 5400 kJ/mol, and that gasoline has an average density of 0.70 g/mL. The density of ethanol is 0.79 g/mL.Assume that the density and heat of combustion of E85 can be obtained by using 85% of the values for ethanol and 15% of the values for gasoline. How much energy could be released by the combustion of 3.0 L of E85?
Ethanol (C2H5OH) is currently blended with gasoline as an automobile fuel.Calculate the mass of CO2 produced per kJ of heat emitted.
When a 0.240-g sample of benzoic acid is combusted in a bomb calorimeter, the temperature rises 1.643 oC . When a 0.270-g sample of caffeine, C8H10O2N4, is burned, the temperature rises 1.523 oC . Using the value 26.38 kJ/g for the heat of combustion of benzoic acid, calculate the heat of combustion per mole of caffeine at constant volume.
When magnesium metal is burned in air, two products are produced. One is magnesium oxide, MgO. The other is the product of the reaction of Mg with molecular nitrogen, magnesium nitride. When water is added to magnesium nitride, it reacts to form magnesium oxide and ammonia gas.The standard enthalpy of formation of solid magnesium nitride is - 461.08 kJmol - 1. Calculate the standard enthalpy change for the reaction between magnesium metal and ammonia gas.
Average Bond Enthalpies (kJ/mol) C-H 413 N-H 391 O-H 463 F-F 155 C-C 348 N-N 163 O-O 146 C=C 614 N-O 201 O=O 495 Cl-F 253 C-N 293 N-F 272 O-F 190 Cl-Cl 242 C-O 358 N-Cl 200 O-Cl 203 Br-F 237 C=O 799 N-Br 243 O-I 234 Br-Cl 218 C-F 485 H-H 436 Br-Br 193 C-Cl 328 H-F 567 C-Br 276 H-Cl 431 I-Cl 208 C-I 240 H-Br 366 I-Br 175 H-I 299 I-I 151 Use the average bond enthalpies in the table to estimate H for the combustion of methanol. l H|H-C-O-H|H
Ammonia (NH3) boils at -33oC; at this temperature it has a density of 0.81 g/cm3. The enthalpy of formation of NH3(g) is -46.2 kJ/mol, and the enthalpy of vaporization of NH3(l) is 23.2 kJ/mol.Calculate the enthalpy change when 4 L of liquid NH3 is burned in air to give N2(g) and H2O(g).
Ammonia (NH3) boils at -33oC; at this temperature it has a density of 0.81 g/cm3. The enthalpy of formation of NH3(g) is -46.2 kJ/mol, and the enthalpy of vaporization of NH3(l) is 23.2 kJ/mol.How does this compare with H for the complete combustion of 1 L of liquid methanol, CH3OH(l)? For CH3OH(l), the density at 25 oC is 0.792 g/cm3, and HfHf equals -239 { m kJ/mol}.
Three common hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation: Hydrocarbon Formula Hf(kJ/mol) 1,3-Butadiene C4 H6 (g) 111.9 1-Butene C4 H8 (g) 1.2 n-Butane C4 H10 (g) -124.7 For 1,3-Butadien calculate the molar enthalpy of combustion to CO2 (g) and H2 O(l).
A gaseous fuel mixture contains 23.1% methane (CH4), 41.1% ethane (C2H6) and the rest propane (C3H8) by volume.When the fuel mixture contained in a 1.53 L tank, stored at 751 mmHg and 298 K, undergoes complete combustion, how much heat is emitted? (Assume that the water produced by the combustion is in the gaseous state.)
Three common hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation: Hydrocarbon Formula Hf(kJ/mol) 1,3-Butadiene C4 H6 (g) 111.9 1-Butene C4 H8 (g) 1.2 n-Butane C4 H10 (g) -124.7 For 1-Butene calculate the molar enthalpy of combustion to CO2 (g) and H2 O(l).
Three common hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation: Hydrocarbon Formula Hf(kJ/mol) 1,3-Butadiene C4 H6 (g) 111.9 1-Butene C4 H8 (g) 1.2 n-Butane C4 H10 (g) -124.7 For n-Butane calculate the molar enthalpy of combustion to CO2 (g) and H2 O(l).
A sample of a hydrocarbon is combusted completely in O2(g) to produce 24.01 g CO2(g), 4.917 g H2O(g), and 342 kJ of heat.Calculate the value of HfHf per empirical-formula unit of the hydrocarbon.
Consider the combustion of a single molecule of CH4(g) forming H2O(l) as a product.How much energy, in J, is produced during this reaction?
Ethanol (C2H5OH) is currently blended with gasoline as an automobile fuel.Calculate the standard enthalpy change for the reaction, assuming H2O(g) as a product.
Calculate the mass of water that can be vaporized with 155 kJ of heat at 100 oC? (Molar Mass of Water= 18.02 g/mol) a. 12.5 gb. 36.0 gc. 68.6 gd. 86.8 ge. 18.02 g 
Methanol (CH3OH) is used as a fuel in race cars. (a) Write a balanced equation for the combustion of liquid methanol in air.
Methanol (CH3OH) is used as a fuel in race cars. (c) Calculate the heat produced by combustion per liter of methanol. Methanol has a density of 0.791 g/mL.
Methanol (CH3OH) is used as a fuel in race cars. (d) Calculate the mass of CO2 produced per kJ of heat emitted. 
Consider the following reaction:CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O(g) If 16.04 g of CH4  completely reacting in the above reaction gives out 802 kJ of heat, what is the ΔH° rxn in kJ for the above reaction?a) -802 kJ                b) -401 kJ                   c) -201 kJ              d) 401 kJ              e) 802 kJ
If the heat of combustion for a specific compound is -1180.0 kJ/mol and its molar mass is 94.65 g/mol how many grams of this compound must you burn to release 465.40 kJ of heat?
Assuming the heat released from the combustion of CH 4 can be used with 100% efficiency, how much CH4 (in g) is required to be combusted in the presence of excess oxygen to warm 1.75 kg of water (Cw= 4.184 J/gK) from 25.0 to 98.0 °C? The enthalpy of combustion of CH4 is -802.3 kJ/mol.A. 56.5 gB. 46.2 gC. 28.7 gD. 10.7 gE. 7.04 g  
What is the minimum energy required to decompose 765 g of PCl 3, according to the reaction below? The molar mass of PCl3 is 137.32 g/mol. 4PCl3(g) → P4(s) + 6Cl2(g)           ΔH°rxn = +1207 kJ a. 2.31 x 103 kJ b. 4.33 x 103 kJ c. 6.72 x 103 kJ d. 1.68 x 103 kJ e. 5.95 x 103 kJ
Given the thermochemical equation 2SO2(g) + O(g) → 2SO3(g), ΔH°rxn = -198 kJ, how much heat is evolved when 600.g of SO2 is burned? a) 5.46 x 10-2 kJ b) 927 kJ c) 1.85 x 103 kJ d) 59,400 kJ e) 3.80 x 103kJ
Carbon monoxide reacts with oxygen to form carbon dioxide by the following reaction:2 CO(g) + O2(g) → 2 CO2(g)∆H for this reaction is −135.28 kcal. How much heat would be released if 18.0 moles of carbon monoxide reacts with 12.0 moles of oxygen?1. 811 kcal2. 1623 kcal3. 2705 kcal4. 216 kcal5. 1218 kcal 6. 29,160 kcal7. 406 kcal
When 1.0 mole of calcium hydroxide is neutralized by hydrochloric acid, ΔH = -111.7 kJ. If you reacted 63.3 mL of a 2.8 M HCl with 33.3 mL of 3.2 M Ca(OH)2. How many kJ of energy would be released? 
The heat of combustion of butane (C4H10) is −2878 kJ/mol. Assume a typical cigarette lighter holds about 1.75 g of butane. How much heat energy would be released if ALL of the butane in the lighter were combusted?1. 86.63 kJ 2. 95.59 kJ3. 40.61 kJ4. 1.05 kJ
The enthalpy of neutralization for the reaction of HNO3 with KOH is given below.HNO3 (aq) + KOH (aq) → H2O (l) + KNO3 (aq)    ΔH = -57.0 kJ102.4 ml of 0.662 M HNO3 is combined with 102.4 ml of 0.662 M KOH in a coffee cup calorimeter. Both of the starting solutions were initially at a temperature of 30.64 °C. The density of each solution is 1.00 g/ml. Calculate the final temperature of the solution in the calorimeter (in °C).
How much energy is required to vaporize 22.7 g of dichloromethane (CH 2Cl2) at its boiling point, if its ΔHvap is 31.6 kJ/mol? The molar mass of dichloromethane is 84.9 g/mol?a) 31.2 kJb) 8.45 kJc) 717 kJd) 15.4 kJe) 18.1 kJ 
Consider the following reaction: CH3OH (g) → CO (g) + 2 H 2 (g)       ΔH = +90.7 kJ(b) Calculate the amount of heat transferred when 45.0 g of CH 3OH (g) is decomposed by this reaction at constant pressure.
Consider the following reaction: CH3OH (g) → CO (g) + 2 H 2 (g)       ΔH = +90.7 kJ(c) For a given sample of CH3OH, the enthalpy change on reaction is 25.8 kJ. How many grams of hydrogen gas are produced? What is the value of ΔH for the reverse of the previous reaction?
Consider the following reaction: CH3OH (g) → CO (g) + 2 H 2 (g)       ΔH = +90.7 kJ(d) How many kilojoules of heat are released when 50.9 g of CO(g) reacts completely with H 2 (g) to form CH3OH(g) at constant pressure?
Consider the combustion of liquid methanol, CH 3OH (l):CH3OH (l) + 3/2 O2 (g) → CO2 (g) + 2 H2O (l)     ΔH = -726.5 kJ(b) Balance the forward reaction with whole-number coefficients. What is ΔH for the reaction represented by this equation? Explain.
Consider the decomposition of liquid benzene, C6H6 (l), to gaseous acetylene, C2H2 (g):C6H6 (l) → 3 C2H2 (g)         ΔH = +630 kJ(b) What is ΔH for the formation of 1 mol of acetylene?
When 5.50 g of Ba(s) is added to 100.00 g of water in a container open to the atmosphere, the reaction shown below occurs and the temperature of the resulting solution rises from 22.00°C to 61.16°C. If the specific heat capacity of the solution is 4.18 J/(g∙°C), calculate ΔH­rxn for the reaction, as written.            Ba(s) + 2 H2O(l)  →  Ba(OH)2(aq) + H2(g)              ΔH­rxn = ?A) –431 kJ          B) –3.14 kJ         C) +3.14 kJ       D) +431 kJ          E) –17.2 kJ
The value of ΔH° for the following reaction is -3351 kJ.2Al(s) + 3O2(g)      →       2Al 2O3(s)What is the ΔH° for the formation of 75.0 g of Al 2O3(s) (kJ)? a. -2.51 x 107b. -1.26 x 105c. -2460d. -1230e. +3351
How much heat is absorbed when 45.00 g of C(s) reacts in the presence of excess SO2(g) to produce CS2(l) and CO(g) according to the following chemical equation?5 C(s) + 2 SO2(g) → CS2(l) + 4 CO(g)    ΔH° = 239.9 kJa. 898.5 kJb. 179.8 kJc. 2158 kJd. 239.9 kJ
In the presence of excess oxygen, methane gas burns in a constant-pressure system to yield carbon dioxide and water:CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) ΔH = -890.0 kJCalculate the value of q (kJ) in this exothermic reaction when 1.70 g of methane is combusted at constant pressure.a. -94.6 kJb. 32.7 kJc. 0.0306 kJd. -9.46 × 104 kJe. -0.0106 kJ
What volume of benzene (C6H6, d= 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 1.5 x 103 kJ of heat according to the following reaction?2 C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g) ΔH°rxn = -6278 kJa. 37 mLb. 75 mLc. 42 mLd. 19 mLe. 21 mL 
Potassium nitrate, KNO3, has a molar mass of 101.1 g/mol. In a constant-pressure calorimeter, 32.3 g of KNO3 is dissolved in 243 g of water at 23.00 °C.KNO3(s)+H2O(aq) ---> KOH(aq)+HNO3(aq)The temperature of the resulting solution decreases to 17.90 °C. Assume the resulting solution has the same specific heat as water, 4.184 J/(g·°C), and that there is negligible heat loss to the surroundings.1. How much heat was released by the solution?2. What is the enthalpy of the reaction?
An LP gas tank in a home barbeque contains 13.2 kg propane (C3H8). Calculate the heat (kJ) associated with the complete combustion of all the propane in the tank.            C3H8   +   5 O2   →   3 CO2   +   4 H2O                        ∆Hrxn = -2044 kJ
Hydrogen peroxide decomposes according to the following thermochemical reaction:                   H2O2   →   H2O   +   ½ O2                            ∆H = -98.2 kJCalculate the change in enthalpy when 1.00 g of hydrogen peroxide decomposes.
Consider the following reaction: C12H22O11 (s) + 12 O2 (g)      →       13 CO 2 (aq) + 11 H2O (l)  in which 25.0 g of sucrose, C12H22O11 , was burned in a bomb calorimeter with a heat capacity of 8.30 kJ / °C . The temperature inside the calorimeter increases by 27.0 °C. Calculate the change in internal energy, ΔE , for the reaction per mole of sucrose. 
A 100.0 mL sample of 0.200 M aqueous hydrochloric acid is added to 100.0 mL of 0.200 M aqueous ammonia in a calorimeter whose heat capacity is negligible. The following reaction occurs when the two solutions are mixed.
A 0.500-L sample of 0.400 M Na2CO3 (aq) is added to 0.500 L of 0.400 M Ba(NO 3)2 (aq) in a calorimeter with a total heat capacity equal to 656 J•K –1 at a constant pressure of one bar. The temperature change is +1.25 K. Use these data to calculate the value of ΔH°rxn for the equation: 
Consider the following thermochemical reaction for the combustion of acetone, C3H6O, the main component of nail polish remover: 
A 21.8 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rises from 25.0 to 62.3°C, determine the heat capacity of the calorimeter. The molar mass of ethanol is 46.07 g/mol.
What volume of benzene (C6H6, d= 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 1.5 x 103 kJ of heat according to the following reaction?
The third step in converting SiO2  to Si is:SiCl4 (g) + 2Mg(s) → 2MgCl2 (s) + Si(s) ΔH = -625.6 kJ. What is the enthalpy change when 4.248 kg of silicon tetrachloride (MW = 169.9 g/mol) is converted to elemental silicon?
Sucrose (table sugar, C12H22O11) can be oxidized to form what two products via a combustion mechanism? What is the enthalpy change when 5.00 g of sugar is burned under conditions of constant pressure, given the standard heat of reaction (ΔrH°) = –5645 kJ/mol•rxn. 
10.1 g CaO is dropped into a Styrofoam coffee cup containing 157 g H2O at 18.0ºC. If the following reaction occurs, what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat? (the specific heat of water = 4.18 J/gºC)
The oxidation of copper(I) oxide, Cu 2O(s), to copper(II) oxide, CuO(s), is an exothermic process,Cu2O(s) + O2(s) → CuO (s)          ΔH rxn = -292 kJCalculate the energy released as heat when 80.38 g of Cu 2O(s) undergo oxidation at constant pressure.
Consider the following reaction:CH4 (g) + 2 O2 (g) → CO2 (g) + 2H2O (l)             ΔH = -891 kJCalculate the enthalpy change for each of the following cases:b. 1.00 x 103 L methane gas at 740. torr and 25°C are burned in excess oxygen. The density of CH4(g) at these conditions is 0.639 g/L.
Calculate ΔH° for the reaction2K (s) + 2 H2O(l) → 2KOH (aq) + H2 (g)A 5.00-g chunk of potassium is dropped into 1.00 kg water at 24.0°C. What is the final temperature of the water after the preceding reaction occurs? Assume that all the heat is used to raise the temperature of the water. (Never run this reaction. It is very dangerous; it bursts into flame!)
The enthalpy of neutralization for the reaction of a strong acid with a strong base is 256 kJ/mol water produced. How much energy will be released when 200.0 mL of 0.400 M HNO3 is mixed with 150.0 mL of 0.500 M KOH?
When 1.00 L of 2.00 M Na2SO4 solution at 30.0°C is added to 2.00 L of 0.750 M Ba(NO3)2 solution at 30.0°C in a calorimeter, a white solid (BaSO4) forms. The temperature of the mixture increases to 42.0°C. Assuming that the specific heat capacity of the solution is 6.37 J/°C ? g and that the density of the final solution is 2.00 g/mL, calculate the enthalpy change per mole of BaSO4 formed.
Consider the dissolution of CaCl2:CaCl2 (s) → Ca2+(aq) + 2 Cl- (aq)          ΔH = -81.5 kJ An 11.0-g sample of CaCl2 is dissolved in 125 g water, with both substances at 25.0°C. Calculate the final temperature of the solution assuming no heat loss to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/°C•g.
Diluting sulfuric acid with water is highly exothermic:H2SO4(l)     H2O ⟶ H2SO4(aq) + heatSuppose you carry out the dilution in a calorimeter. The initial T is 25.0°C, and the specific heat capacity of the final solution is 3.50 J/g•K. What is the final T?
Consider the reaction2HCl (aq) + Ba(OH)2 (aq) → BaCl2 (aq) + 2H2O (l)         ΔH = -118 kJ Calculate the heat when 100.0 mL of 0.500 M HCl is mixed with 300.0 mL of 0.100 M Ba(OH)2. Assuming that the temperature of both solutions was initially 25.0°C and that the final mixture has a mass of 400.0 g and a specific heat capacity of 4.18 J/°C ? g, calculate the final temperature of the mixture.
The heat of combustion of ethanol, C2 H5 OH(l), is -1367 kJ/mol. A batch of sauvignon blanc wine contains 11.6 % ethanol by mass.Assuming the density of the wine to be 1.0 g/mL, what is the caloric content due to the alcohol (ethanol) in a 6-oz glass of wine (177 mL)?
Zinc metal reacts with hydrochloric acid according to the following balanced equation: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g). When 0.116 g of Zn(s) is combined with enough HCl to make 52.6 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.1˚C to 24.3˚C. Find ΔHrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/g•˚C as the specific heat capacity.)
A pound of plain M&M candies contains 96 g fat, 320 g carbohydrate, and 21 g protein.Table 5.5: Compositions and Fuel ValuesFuelValuekcal/g(Cal/g)(Pages 191 - 192)Carbohydrate174Fat389Protein174What is the fuel value in kJ in a 46-g (about 1.6 oz) serving?        
Propane, C3H8, is a hydrocarbon that is commonly used as a fuel.Assuming that all of the heat released in burning 25.0 grams of propane is transferred to 4.00 kilograms of water, calculate the increase in temperature of the water.
A 30.5-g sample of an alloy at 93.0°C is placed into 50.0 g of water at 22.0°C in an insulated coffee-cup calorimeter with a heat capacity of 9.2 J/K. If the final temperature of the system is 31.1°C, what is the specific heat capacity of the alloy?
When 25.0 mL of 0.500 M H 2SO4 is added to 25.0 mL of 1.00 M KOH in a coffee-cup calorimeter at 23.50°C, the temperature rises to 30.17°C. Calculate ΔH in kJ per mole of H2O formed. (Assume that the total volume is the sum of the volumes and that the density and specific heat capacity of the solution are the same as for water.)
When 20.0 mL of 0.200 M AgNO 3 and 30.0 mL of 0.100 M NaCl, both at 24.72°C, are mixed in a coffee-cup calorimeter, AgCl precipitates and the temperature of the mixture increases to 25.65°C. Calculate ΔH in kJ per mole of AgCl(s) produced. (Assume that the total volume is the sum of the volumes and that the density and specific heat capacity of the solution are the same as for water.)
When a 2.150-g sample of glucose, C6H12O6, is burned in a bomb calorimeter with a heat capacity of 6.317 kJ/K, the temperature of the calorimeter increases from 23.446°C to 28.745°C. Calculate ΔE for the combustion of glucose in kJ/mol.
A chemist places 1.750 g of ethanol, C 2H6O, in a bomb calorimeter with a heat capacity of 12.05 kJ/K. The sample is burned and the temperature of the calorimeter increases by 4.287°C. Calculate ΔE for the combustion of ethanol in kJ/mol.
High-purity benzoic acid (C 6H5COOH; ΔH for combustion = −3227 kJ/mol) is used to calibrate bomb calorimeters. A 1.221-g sample burns in a calorimeter that has a heat capacity of 6.384 kJ/°C. What is the temperature change?
Two aircraft rivets, one iron and the other copper, are placed in a calorimeter that has an initial temperature of 20.°C. The data for the rivets are as follows:Will heat flow from Fe to Cu or from Cu to Fe?
In a coffee-cup calorimeter, 150.0 mL of 0.50 M HCl is added to 50.0 mL of 1.00 M NaOH to make 200.0 g solution at an initial temperature of 48.2°C. If the enthalpy of neutralization for the reaction between a strong acid and a strong base is 256 kJ/mol, calculate the final temperature of the calorimeter contents. Assume the specific heat capacity of the solution is 4.184 J/g•°C and assume no heat loss to the surroundings.
Two aircraft rivets, one iron and the other copper, are placed in a calorimeter that has an initial temperature of 20.°C. The data for the rivets are as follows:What other information is needed to correct any measurements in an actual experiment?
Two aircraft rivets, one iron and the other copper, are placed in a calorimeter that has an initial temperature of 20.0°C. The data for the rivets are as follows:What is the maximum final temperature of the system (assuming the heat capacity of the calorimeter is negligible)?
Find ΔH for the combustion of ethanol (C2H6O) to carbon dioxide and liquid water from the following data. The heat capacity of the bomb calorimeter is 34.65 kJ/K and the combustion of 1.761 g of ethanol raises the temperature of the calorimeter from 294.26 K to 295.77 K .
A chemical engineer burned 1.520 g of a hydrocarbon in the bomb of a calorimeter (see Figure 6.10). The water temperature rose from 20.00°C to 23.55°C. If the calorimeter had a heat capacity of 11.09 kJ/K, what was the heat released (qV) per gram of hydrocarbon?
Three of the reactions that occur when the paraffin of a candle (typical formula C21H44) burns are as follows:(1) Complete combustion forms CO2 and water vapor.(2) Incomplete combustion forms CO and water vapor.(3) Some wax is oxidized to elemental C (soot) and water vapor.Find q (in kJ) when a 254-g candle burns completely.
In a coffee-cup calorimeter, 50.0 mL of 0.100 M AgNO3 and 50.0 mL of 0.100 M HCl are mixed to yield the following reaction:Ag+ (aq) + Cl- (aq) → AgCl (s)The two solutions were initially at 22.60°C, and the final temperature is 23.40°C. Calculate the heat that accompanies this reaction in kJ/mol of AgCl formed. Assume that the combined solution has a mass of 100.0 g and a specific heat capacity of 4.18 J/°C ? g.
Three of the reactions that occur when the paraffin of a candle (typical formula C21H44) burns are as follows:(1) Complete combustion forms CO2 and water vapor.(2) Incomplete combustion forms CO and water vapor.(3) Some wax is oxidized to elemental C (soot) and water vapor.Find q (in kJ) when 8.00% by mass of the candle burns incompletely and 5.00% by mass of it undergoes soot formation.
Consider the following reaction:2H2 + O2 → 2H2O   ΔH = -572 kJa. How much heat is evolved for the production of 1.00 mole of H2O(l)?
A 0.500 g sample of KCl is added to 50.0 g of water in a calorimeter (Figure 5.12). If the temperature decreases by 1.05°C, what is the approximate amount of heat involved in the dissolution of the KCl, assuming the specific heat of the resulting solution is 4.18 J/g°C? Is the reaction exothermic or endothermic?
Dissolving 3.0 g of CaCl2(s) in 150.0 g of water in a calorimeter (Figure 5.12) at 22.4°C causes the temperature to rise to 25.8°C. What is the approximate amount of heat involved in the dissolution, assuming the specific heat of the resulting solution is 4.18 J/g°C? Is the reaction exothermic or endothermic?
When 50.0 g of 0.200 M NaCl(aq) at 24.1°C is added to 100.0 g of 0.100 M AgNO3(aq) at 24.1°C in a calorimeter, the temperature increases to 25.2°C as AgCl(s) forms. Assuming the specific heat of the solution and products is 4.20 J/g°C, calculate the approximate amount of heat in joules produced.
A 1.800-g sample of solid phenol (C6H5OH(s)) was burned in a bomb calorimeter, which has a total heat capacity of 11.66 kJ/oC. The temperature of the calorimeter plus its contents increased from 21.36oC to 26.37oC.You may want to reference (Pages 178 - 183)Section 5.5 while completing this problem.What is the heat of combustion per mole of phenol?
The addition of 3.15 g of Ba(OH) 2∙8H2O to a solution of 1.52 g of NH 4SCN in 100 g of water in a calorimeter caused the temperature to fall by 3.1°C. Assuming the specific heat of the solution and products is 4.20 J/g°C, calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation:Ba(OH)2∙8H2O(s) + 2NH4SCN(aq) ⟶ Ba(SCN)2(aq) + 2NH3(aq) + 10H2O(l)
The reaction of 50 mL of acid and 50 mL of base described in Example 5.5 increased the temperature of the solution by 6.9°C. How much would the temperature have increased if 100 mL of acid and 100 mL of base had been used in the same calorimeter starting at the same temperature of 22.0°C? Explain your answer.
Silver bromide is used to coat ordinary black-and-white photographic film, while high-speed film uses silver iodide.a) When 50.0 mL of 5.0 g/L AgNO 3 is added to a coffee-cup calorimeter containing 50.0 mL of 5.0 g/L NaI, with both solutions at 25°C, what mass of AgI forms?
Silver bromide is used to coat ordinary black-and-white photographic film, while high-speed film uses silver iodide.(a) When 50.0 mL of 5.0 g/L AgNO3 is added to a coffee-cup calorimeter containing 50.0 mL of 5.0 g/L NaI, with both solutions at 25°C, what mass of AgI forms?(b) Use Appendix B to find ΔH°rxn.
Consider the following reaction:2H2 + O2 → 2H2O   ΔH = -572 kJb. How much heat is evolved when 4.03 g hydrogen are reacted with excess oxygen?
Consider the following reaction:2H2 + O2 → 2H2O   ΔH = -572 kJc. How much heat is evolved when 186 g oxygen are reacted with excess hydrogen?
Silver bromide is used to coat ordinary black-and-white photographic film, while high-speed film uses silver iodide.a) When 50.0 mL of 5.0 g/L AgNO 3 is added to a coffee-cup calorimeter containing 50.0 mL of 5.0 g/L NaI, with both solutions at 25°C, what mass of AgI forms?b) Find ΔH°rxn.c)What is ΔTsoln (assuming the volumes are additive and the solution has the density and specific heat capacity of water)?
Before the introduction of chlorofluorocarbons, sulfur dioxide (enthalpy of vaporization, 6.00 kcal/mol) was used in household refrigerators. What mass of SO2 must be evaporated to remove as much heat as evaporation of 1.00 kg of CCl2F2 (enthalpy of vaporization is 17.4 kJ/mol)?The vaporization reactions for SO2 and CCl2F2 are SO2(l) ⟶ SO2(g) and CCl2F(l) ⟶ CCl2F2(g), respectively.
Acetylene gas (ethyne; HC≡CH) burns in an oxyacetylene torch to produce carbon dioxide and water vapor. The enthalpy of reaction for the combustion of acetylene is 1259 kJ/mol.(a) Calculate the C≡C bond energy, and compare your value with the following table.(b) When 500.0 g of acetylene burns, how many kilojoules of heat are given off?(c) How many grams of CO2 form?
The calorie (4.184 J) is defined as the quantity of energy needed to raise the temperature of 1.00 g of liquid water by 1.00°C. The British thermal unit (Btu) is defined as the quantity of energy needed to raise the temperature of 1.00 lb of liquid water by 1.00°F.How many moles of methane must be burned to give 1.00 therm of energy? (Assume that water forms as a gas.)
Homes may be heated by pumping hot water through radiators. What mass of water will provide the same amount of heat when cooled from 95.0 to 35.0°C, as the heat provided when 100 g of steam is cooled from 110°C to 100°C.
The calorie (4.184 J) is defined as the quantity of energy needed to raise the temperature of 1.00 g of liquid water by 1.00°C. The British thermal unit (Btu) is defined as the quantity of energy needed to raise the temperature of 1.00 lb of liquid water by 1.00°F.If natural gas costs $0.66 per therm, what is the cost per mole of methane? (Assume that natural gas is pure methane.)
The calorie (4.184 J) is defined as the quantity of energy needed to raise the temperature of 1.00 g of liquid water by 1.00°C. The British thermal unit (Btu) is defined as the quantity of energy needed to raise the temperature of 1.00 lb of liquid water by 1.00°F.How much would it cost to warm 318 gal of water in a hot tub from 15.0°C to 42.0°C by burning methane (1 gal = 3.78 L)?
Butane combusts according to the equation: C4H10(g) + 13/2 O2(g) → 4 CO2(g) + 5 H2O(g); ΔH˚rxn = -2658 kJ. What mass of butane in grams is necessary to produce 2.1×103 kJ  kJ of heat?
Butane combusts according to the equation: C4H10(g) + 13/2 O2(g) → 4 CO2(g) + 5 H2O(g); ΔH˚rxn = -2658 kJ. What mass of CO2 is produced in the evolution of 2.1×103 kJ  kJ of heat?
Titanium reacts with iodine to form titanium(III) iodide, emitting heat, via the following reaction: 2 Ti(s) + 3 I2(g) → 2 TiI3(s); ΔH˚rxn= -839 kJ. Determine the mass of titanium that reacts if 1.61×103 kJ of heat is emitted by the reaction.
Titanium reacts with iodine to form titanium(III) iodide, emitting heat, via the following reaction: 2 Ti(s) + 3 I2(g) → 2 TiI3(s); ΔH˚rxn= -839 kJ. Determine the mass of iodine that reacts if 1.61×103 kJ of heat is emitted by the reaction.
A stalk of celery has a caloric content (fuel value) of 9.0 kcal. If 1.0 kcal is provided by fat and there is very little protein, estimate the number of grams of carbohydrate and fat in the celery.
The enthalpy of combustion of hard coal averages −35 kJ/g, that of gasoline, 1.28 x 105 kJ/gal. How many kilograms of hard coal provide the same amount of heat as is available from 1.0 gallon of gasoline? Assume that the density of gasoline is 0.692 g/mL (the same as the density of isooctane).
LP gas burns according to the following exothermic reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g); ΔH˚rxn= -2044 kJ. What mass of LP gas is necessary to heat 1.6 L of water from room temperature (25.0˚C) to boiling (100.0˚C)? Assume that during heating, 16% of the heat emitted by the LP gas combustion goes to heat the water. The rest is lost as heat to the surroundings.
During a recent winter month in Sheboygan, Wisconsin, it was necessary to obtain 3500 kWh of heat provided by a natural gas furnace with 89% efficiency to keep a small house warm (the efficiency of a gas furnace is the percent of the heat produced by combustion that is transferred into the house).How many gallons of LPG (liquefied petroleum gas) would be required to replace the natural gas used? Assume the LPG is liquid propane [C3H8: density, 0.5318 g/mL; enthalpy of combustion, 2219 kJ/mol for the formation of CO2(g) and H2O(l)] and the furnace used to burn the LPG has the same efficiency as the gas furnace.
A large sport utility vehicle has a mass of 2600 kg. Calculate the mass of CO2 emitted into the atmosphere upon accelerating the SUV from 0.0 mph to 66.0 mph. Assume that the required energy comes from the combustion of octane with 30% efficiency. (Hint: Use KE = 1/2mv2 to calculate the kinetic energy required for the acceleration.)
Combustion of natural gas (primarily methane) occurs in most household heaters. The heat given off in this reaction is used to raise the temperature of the air in the house. Assuming that all the energy given off in the reaction goes to heating up only the air in the house, determine the mass of methane required to heat the air in a house by 15.0 ˚C. Assume each of the following: house dimensions are 35.0m x 35.0m x 3.2 m; specific heat capacity of air is 30 J/K•mol; 1.00  m mol of air occupies 22.4 L{ m{ L}} for all temperatures concerned.
The complete combustion of acetylene, C2H2(g), produces 1300. kJ of energy per mole of acetylene consumed. How many grams of acetylene must be burned to produce enough heat to raise the temperature of 1.00 gal water by 10.0°C if the process is 80.0% efficient? Assume the density of water is 1.00 g/cm3.
It has been determined that the body can generate 5500 kJ of energy during one hour of strenuous exercise. Perspiration is the body’s mechanism for eliminating this heat. What mass of water would have to be evaporated through perspiration to rid the body of the heat generated during 2 hours of exercise? (The heat of vaporization of water is 40.6 kJ/mol.)
Hydrogen gas reacts with oxygen to form water.2 H2(g) + O2(g) → 2 H2O(g)         ΔH = –483.5 kJ/molDetermine the minimum mass of hydrogen gas required to produce 366 kJ of heat.
Natural gas burns in air to form carbon dioxide and water, releasing heat.CH4(g) + O2(g) → CO2(g) + H2O(g); ΔHrxn˚ = –802.3 kJ/molWhat minimum mass of CH4 is required to heat 65.0 g of water by 26.0˚C? (Assume 100% heating efficiency.) (For water, Cs= 4.18 J/g•˚C).
The propane fuel (C3H8) used in gas barbecues burns according to the following thermochemical equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g); ΔH˚rxn= -2044 kJ. If a pork roast must absorb 1700 J to fully cook, and if only 13% of the heat produced by the barbecue is actually absorbed by the roast, what mass of CO2 is emitted into the atmosphere during the grilling of the pork roast?
Consider the following reaction: 2 Mg(s) + O2(g) → 2 MgO(s), ΔH = –1204 kJHow many grams of MgO are produced during an enthalpy change of –234 kJ ?
Meals-ready-to-eat (MREs) are military meals that can be heated on a flameless heater. The heat is produced by the following reaction: Mg(s) + 2 H2O(l) → Mg(OH)2(s) + H2(g).Calculate the number of grams of Mg needed for this reaction to release enough energy to increase the temperature of 76 mL of water from 26˚C to 76˚C.
Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars a day. Theactual process requires water, but a simplified equation is4Fe (s) + 3O2 (g) ⟶ 2Fe2O3 (s)             Δ H = −1.65 x 10 3 kJHow much rust forms when 4.85 x 10 3 kJ of heat is released?
Determine the mass of CO2 produced by burning enough of methane to produce 2.25x102 kJ of heat.CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g); ΔH˚rxn= -802.3 kJ
Determine the mass of CO2 produced by burning enough of propane to produce 2.25x102 of heat.C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g); H˚rxn= - 2217 kJ
You may want to reference (Pages 172 - 176)Section 5.3 while completing this problem.Consider the following reaction: 2 CH3OH(g) → 2 CH4(g) + O2(g), ΔH = +252.8 kJFor a given sample of CH3OH, the enthalpy change during the reaction is 82.6 kJ. What mass of methane gas is produced? 
Determine the mass of CO2 produced by burning enough of octane to produce 2.25x102 of heat.C8H18(l) + 25/2 O2(g) → 8 CO2(g) + 9 H2O(g); ΔH˚rxn= - 5074.1 kJ
The world burns the fossil fuel equivalent of 6x1012 kg of petroleum per year. Assume that all of this petroleum is in the form of octane (C8H18). Calculate how much CO2 (in kg) the world produces from fossil fuel combustion per year. (Hint: Begin by writing a balanced equation for the combustion of octane.)
Most ethylene (C2H4), the starting material for producing polyethylene, comes from petroleum processing. It also occurs naturally as a fruit-ripening hormone and as a component of natural gas. How many grams of C2H4 must burn to give 70.0 kJ of heat?
How many moles of isooctane must be burned to produce 100 kJ of heat under standard state conditions?
What mass of carbon monoxide must be burned to produce 175 kJ of heat under standard state conditions?
What mass of natural gas (CH4) must you burn to emit 268 kJ of heat?CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)             Hrxno= –802.3 kJ/mol
Charcoal is primarily carbon. What mass of CO2 is produced if you burn enough carbon (in the form of charcoal) to produce 5.10 x 102 kJ of heat? The balanced chemical equation is as follows:C(s) + O2(g) → CO2(g), ΔHrxn = –393.5 kJ/mol
Consider the combustion of propane:C3H8 + 5O2 → 3CO2 + 4H2O           ΔH = -2221 kJAssume that all the heat in Example 7‑3 comes from the combustion of propane. What mass of propane must be burned to furnish this amount of energy assuming the heat transfer process is 60.% efficient?
5.43Consider the following reaction:2Mg(s) + O2 (g) → 2MgO(s)  ΔH = - 1204 kJHow many grams of MgO are produced during an enthalpy change of -234 kJ?
What volume of benzene (C6H6, d = 0.88 g/mL, molar mass = 78.11 g/mol) is required to produce 1.5 x 103 kJ heat according to the following reaction?2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2(g)     ΔH°rxn = -6278 kJa. 37 mLb. 21 mLc. 42 mLd. 19 mLe. 75 mL
Acetylene gas (ethyne; HC≡CH) burns in an oxyacetylene torch to produce carbon dioxide and water vapor. The enthalpy of reaction for the combustion of acetylene is 1259 kJ/mol.(a) Calculate the C≡C bond energy, and compare your value with the following table.(b) When 500.0 g of acetylene burns, how many kilojoules of heat are given off?
Consider the following reaction:CH4 (g) + 2 O2 (g) → CO2 (g) + 2H2O (l)             ΔH = -891 kJCalculate the enthalpy change for each of the following cases: a. 1.00 g methane is burned in excess oxygen.
Acetylene gas (ethyne; HC≡CH) burns in an oxyacetylene torch to produce carbon dioxide and water vapor. The enthalpy of reaction for the combustion of acetylene is 1259 kJ/mol.(a) Calculate the C≡C bond energy, and compare your value with the following table.(b) When 500.0 g of acetylene burns, how many kilojoules of heat are given off?(c) How many grams of CO2 form?(d) How many liters of O 2 at 298 K and 18.0 atm are consumed?
The decomposition of ZnCO3(s) into ZnO(s) and CO2(g) at constant pressure requires the addition of 71.5 kJ of heat per mole of ZnCO3.What is the enthalpy of the reaction above?
Ammonia reacts with oxygen according to the equation: 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g); ΔHrxn = -906 kJ. Calculate the heat (in kJ) associated with the complete reaction of 265 g of NH3.
The addition of hydrochloric acid to a silver nitrate solution precipitates silver chloride according to the reaction:AgNO3(aq) + HCl(aq) → AgCl(s) + HNO3(aq)When 50.0 mL of 0.100 M AgNO3 is combined with 50.0 mL of 0.100 M HCl in a coffee-cup calorimeter, the temperature changes from 23.40˚C to 24.21˚C. Calculate ΔHrxn for the reaction as written. Use 1.00 g/mL as the density of the solution and Cs = 4.18 J/(g • ˚C) as the specific heat capacity of the solution.
A propane tank on a home barbeque contains 11.3x103 g of propane. Use the value for ΔHrxn (-2044 kJ/mol) to calculate the total amount of heat produced when the entire contents of the tank of propane is burned.
The reusable booster rockets of the space shuttle use a mixture of aluminum and ammonium perchlorate as fuel. A possible reaction is3Al (s) + 3NH4ClO4 (s) → Al2O3 (s) + AlCl3 (s) + 3NO (g) + 6H2O (g) The space shuttle Orbiter utilizes the oxidation of methylhydrazine by dinitrogen tetroxide for propulsion:4N2H3CH3 (l) + 5N2O4 (l) →  12H2O (g) + 9N2 (g) + 4CO2 (g)Which reaction produces more energy per kilogram of reactant mixture (stoichiometric amounts)?
Calculate ΔH for the reaction described by the equation. (Hint: use the value for the approximate amount of heat absorbed by the reaction that you calculated in a previous exercise.)Ba(OH)2·8H2 O(s) + 2NH4SCN(aq) ⟶ Ba(SCN)2(aq) + 2NH3(aq) + 10H2O(l)
An aqueous waste stream with a maximum concentration of 0.50 M H 2SO4 (d = 1.030 g/mL at 25°C) is neutralized by controlled addition of 40% NaOH (d = 1.430 g/L) before it goes to the process sewer and then to the chemical plant waste treatment facility. A safety review finds that the waste stream could meet a small stream of an immiscible organic compound, which could form a flammable vapor in air at 40.°C. The maximum temperature reached by the NaOH solution and the waste stream is 31°C. Could the temperature increase due to the heat transferred by the neutralization cause the organic vapor to explode? Assume that the specific heat capacity of each solution is 4.184 J/g⋅K.
Consider the following thermochemical equation for the combustion of acetone (C3H6O), the main ingredient in nail polish remover: C3H6O(l) + 4 O2(g) → 3 CO2(g) + 3 H2O(g), ΔH˚rxn = -1790 kJ. If a bottle of nail polish remover contains 177 mL of acetone, how much heat would be released by its complete combustion? The density of acetone is 0.788 g/mL.
Nitromethane (CH3NO2) burns in air to produce significant amounts of heat: 2 CH3NO2(l) + 3/2 O2(g) → 2 CO2(g) + 3 H2O(l) + N2(g); ΔH˚rxn = -1418 kJ.How much heat is produced by the complete reaction of 5.29 kg of nitromethane?
Diluting sulfuric acid with water is highly exothermic:H2SO4(l)     H2O ⟶ H2SO4(aq) + heatFind ΔH°rxn for diluting 1.00 mol of H2SO4(l) (d = 1.83 g/mL) to 1 L of 1.00 M H 2SO4(aq) (d = 1.060 g/mL).
A balloonist begins a trip in a helium-filled balloon in early morning when the temperature is 15°C. By mid-afternoon, the temperature is 30.°C. Assuming the pressure remains at 1.00 atm, for each mole of helium, calculate ΔH  for the process (in J).
Water gas, a mixture of H2 and CO, is an important industrial fuel produced by the reaction of steam with red hot coke, essentially pure carbon: C(s) + H2O(g) ⟶ CO(g) + H2(g).Calculate the heat of combustion of 1 mole of liquid methanol to H 2O(g) and CO2(g).
Consider the decomposition of liquid benzene, C6H6(l), to gaseous acetylene, C2H2(g): C6H6(l) → 3 C2H2(g), ΔH = +630 kJWhat is ΔH for the formation of 1 mol of acetylene?
Ethanol, C2H5OH, is used as a fuel for motor vehicles, particularly in Brazil.The density of ethanol is 0.7893 g/mL. Calculate the enthalpy of combustion of exactly 1 L of ethanol.
C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(l), Δ;;;;;;H = –2803 kJBased on the enthalpy of the above reaction, what is the fuel value of glucose on a per gram basis?
Electric generating plants transport large amounts of hot water through metal pipes, and oxygen dissolved in the water can cause a major corrosion problem. Hydrazine (N2H4) added to the water prevents this problem by reacting with the oxygen:N2H4(aq) + O2(g) ⟶ N2(g) + 2H2O(l)About 4 x 107 kg of hydrazine is produced every year by reacting ammonia with sodium hypochlorite in the Raschig process:2NH3(aq) + NaOCl(aq) ⟶ N2H4(aq) + NaCl(aq) + H2O(l)    ΔH°rxn = −151 kJWhat is the heat released when aqueous N 2H4 is added to 5.00 x 10 3 L of water that is 2.50 x 10−4 M O2?
The oxidation of the sugar glucose, C6H12O6, is described by the following equation:C6H12O6(s) + 6O2(g) ⟶ 6CO2(g) + 6H2O(l)        ΔH = −2816 kJThe metabolism of glucose gives the same products, although the glucose reacts with oxygen in a series of steps in the body.How much heat in kilojoules can be produced by the metabolism of 1.0 g of glucose?
The oxidation of the sugar glucose, C6H12O6, is described by the following equation:C6H12O6(s) + 6O2(g) ⟶ 6CO2(g) + 6H2O(l)        ΔH = −2816 kJThe metabolism of glucose gives the same products, although the glucose reacts with oxygen in a series of steps in the body.How many Calories can be produced by the metabolism of 1.0 g of glucose?
Liquid methanol (CH3OH) can be used as an alternative fuel by pickup trucks and SUVs. An industrial method for preparing it involves the catalytic hydrogenation of carbon monoxide:CO(g) + 2H2(g) catalyst⟶ CH3OH(l)How much heat (in kJ) is released when 15.0 L of CO at 85°C and 112 kPa reacts with 18.5 L of H 2 at 75°C and 744 torr?
Three common hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation:HydrocarbonFormulaΔH˚f(kJ/mol)1,3-ButadieneC4H6(g)111.91-ButeneC4H8(g)1.2n-ButaneC4H10(g)–124.7For 1,3-Butadiene, calculate the fuel value in kJ/g.
Three common hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation:HydrocarbonFormulaHf(kJ/mol)1,3-ButadieneC4 H6 (g)111.91-ButeneC4 H8 (g)1.2n-ButaneC4 H10 (g)-124.7Propose a relationship between hydrogen content and fuel value in hydrocarbons.
You may want to reference (Pages 191 - 192) Section 5.8 while completing this problem.The sun supplies about 1.1 kilowatt(s) of energy for each square meter of surface area (1.1 kW/m2, where a watt = 1 J/s). Plants produce the equivalent of about 0.21 g of sucrose (C12H22O11) per hour per square meter.Assuming that the sucrose is produced as follows, calculate the percentage of sunlight used to produce sucrose.12 CO2(g) + 11 H2O(l) → C12H22O11 + 12O2(g), ΔH = 5645kJ
It is estimated that the net amount of carbon dioxide fixed by photosynthesis on the landmass of the Earth is 5.5 x 1016 g of CO2. All this carbon is converted into glucose. Calculate the energy stored by photosynthesis on land per year in kJ.12 CO2(g) + 11 H2O(l) → C12H22O11 + 12O2(g), ΔH = 5645kJ
It is estimated that the net amount of carbon dioxide fixed by photosynthesis on the landmass of the Earth is 5.5 x 1016 g of CO2. All this carbon is converted into glucose.Calculate the average rate of conversion of solar energy into plant energy in MW (1W = 1J/s). A large nuclear power plant produces about 103 kJ. The energy of how many such nuclear power plants is equivalent to the solar energy conversion?12 CO2(g) + 11 H2O(l) → C12H22O11 + 12O2(g), ΔH = 5645kJ
The thermite reaction, Fe2O3(s) + 2Al(s)  →  2Fe(s) + Al2O3(s), Ho= -851.5kJ/mol, is one of the most exothermic reactions known. Because the heat released is sufficient to melt the iron product, the reaction is used to weld metal under the ocean.How much heat is released per mole of Al2O3 produced?
The methane molecule, CH4, has the geometry shown in following figure. Imagine a hypothetical process in which the methane molecule is "expanded," by simultaneously extending all four C–H bonds to infinity. We then have the process CH4(g) → C(g) + 4 H(g).Suppose that 3.45 g CH4(g) reacts with 1.22 g F2(g), forming CF4(g) and HF(g) as sole products. If the reaction occurs at constant pressure, what amount of heat is evolved?
Consider the following balanced thermochemical equation for the decomposition of the mineral magnesite:MgCO3 (s) ⟶ MgO (s) + CO2 (g)                         ΔH = 117.3 kJWhat is ΔH when 5.35 mol of CO2 reacts with excess MgO?
Manganese reacts with hydrochloric acid to produce manganese(II) chloride and hydrogen gas.Mn(s) + 2 HCl(aq) → MnCl2(aq) + H2(g)When 0.630 g Mn is combined with enough hydrochloric acid to make 100.0 mL of solution in a coffee-cup calorimeter, all of the Mn reacts, raising the temperature of the solution from 23.6 ˚C to 28.8 ˚C.Find ΔHrxn for the reaction as written. (Assume that the specific heat capacity of the solution is 4.18 J/g • ˚C and the density is 1.00 g/mL)
Consider the following balanced thermochemical equation for the decomposition of the mineral magnesite:MgCO3 (s) ⟶ MgO (s) + CO2 (g)                         ΔH = 117.3 kJWhat is ΔH when 35.5 g of CO2 reacts with excess MgO?
Liquid hydrogen peroxide, an oxidizing agent in many rocket fuel mixtures, releases oxygen gas on decomposition:2H2O2 (l ) ⟶ 2H2O (l) + O2 (g)               Δ H = −196.1 kJHow much heat is released when 652 kg of H 2O2 decomposes?
Consider the following reaction: 2 Mg(s) + O2(g) → 2 MgO(s), ΔH = –1204 kJCalculate the amount of heat transferred when 3.56 g of Mg(s) reacts at constant pressure.
When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl–(aq) → AgCl(s), ΔH = –65.5 kJCalculate ΔH for formation of 0.460 mol of AgCl by this reaction.
When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl–(aq) → AgCl(s), ΔH = –65.5 kJCalculate ΔH for the formation of 8.00 g of AgCl.
When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl–(aq) → AgCl(s), ΔH = –65.5 kJCalculate ΔH when 9.25×10−4 mol of AgCl dissolves in water.
At one time, a common means of forming small quantities of oxygen gas in the laboratory was to heat KClO3: 2 KClO3(s) → 2 KCl(s) + 3 O2(g), ΔH = –89.4kJFor this reaction, calculate ΔH for the formation of 1.36 mol of O2.
At one time, a common means of forming small quantities of oxygen gas in the laboratory was to heat KClO3: 2 KClO3(s) → 2 KCl(s) + 3 O2(g), ΔH = –89.4kJFor this reaction, calculate ΔH for the formation of 10.6 g of KCl.
Calculate the enthalpy of solution (ΔH for the dissolution) per mole of CaCl 2 (refer to exercise 25).
Ozone, O3(g), is a form of elemental oxygen that is important in the absorption of ultraviolet radiation in the stratosphere. It decomposes to O2(g) at room temperature and pressure according to the following reaction: 2 O3(g) → 3 O2(g), ΔH = –284.6 kJWhat is the enthalpy change for this reaction per mole of O3(g)?
Although the gas used in an oxyacetylene torch (Figure 5.7) is essentially pure acetylene, the heat produced by combustion of one mole of acetylene in such a torch is likely not equal to the enthalpy of combustion of acetylene listed in Table 5.2. Considering the conditions for which the tabulated data are reported, suggest an explanation.
Ozone, O3(g), is a form of elemental oxygen that is important in the absorption of ultraviolet radiation in the stratosphere. It decomposes to O2(g) at room temperature and pressure according to the following reaction: 2 O3(g) → 3 O2(g), ΔH = –284.6 kJWhich has the higher enthalpy under these conditions, 2 O3 (g) or 3 O2 (g)?
You may want to reference (Pages 172 - 176)Section 5.3 while completing this problem.Consider the following reaction: 2 CH3OH(g) → 2 CH4(g) + O2(g), ΔH = +252.8 kJCalculate the amount of heat transferred when 26.0 g of CH3OH (g) is decomposed by this reaction at constant pressure.
How much heat is produced by burning 4.00 moles of acetylene under standard state conditions?
You may want to reference (Pages 172 - 176)Section 5.3 while completing this problem.Consider the following reaction: 2 CH3OH(g)  →  2CH4(g) + O2 (g), ΔH = +252.8 kJHow many kilojoules of heat are released when 38.5 g of CH4(g) reacts completely with O2(g) to form CH3OH(g) at constant pressure?
How much heat is produced by combustion of 125 g of methanol under standard state conditions?
When 2.50 g of methane burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion per mole of methane under these conditions?
How much heat is produced when 100 mL of 0.250 M HCl (density, 1.00 g/mL) and 200 mL of 0.150 M NaOH (density, 1.00 g/mL) are mixed?HCl(aq) + NaOH(aq) ⟶ NaCl(aq) + H2O(l)       ΔH°298 = −58 kJIf both solutions are at the same temperature and the heat capacity of the products is 4.19 J/g °C, how much will the temperature increase? What assumption did you make in your calculation?
Methanol (CH3OH) is used as a fuel in race cars.You may want to reference (Pages 187 - 190) Section 5.7 while completing this problem.Write a balanced equation for the combustion of liquid methanol in air, assuming H2O(g) as a product.   Calculate the standard enthalpy change for the combustion of 1 mol of liquid methanol, assuming H2O(g) as a product. (Refer to Appendix C (Pages 1088 - 1091) to find the respective standard enthalpies of formation.)        
Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction:NH4NO3 (s)  →  NH4+(aq) + NO3–(aq)In order to measure the enthalpy change for this reaction, 1.25 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8 ˚C and the final temperature (after the solid dissolves) is 21.9 ˚C. Calculate the change in enthalpy for the reaction. (Use 1.0 g/mL as the density of the solution and 4.18 J/(g • ˚C) as the specific heat capacity.)
5.43Consider the following reaction:2Mg(s) + O2 (g) → 2MgO(s)  ΔH = - 1204 kJCalculate the amount of heat transferred when 3.55 g of Mg(s) reacts at constant pressure.
5.43Consider the following reaction:2Mg(s) + O2 (g) → 2MgO(s)  ΔH = - 1204 kJHow many kilojoules of heat are absorbed when 40.3 g of MgO(s) is decomposed into Mg(s) and O2(g) at constantpressure?
The oxidation of copper 1 oxide, Cu 2O(s) to copper 2 oxide, CuO(s) is an exothermic process:2Cu2O(s) + O2(g) → 4CuO (s)       ΔH= -292.0 kJ x mol -1Calculate the energy released as heat when 25.0 grams of Cu2O (s) undergo oxidation at constant pressure.
Compounds of boron and hydrogen are remarkable for their unusual bonding and also for their reactivity. With the more reactive halogens, for example, diborane (B2H6) forms trihalides even at low temperatures:B2H6 (g) + 6Cl2 (g) ⟶ 2BCl3 (g) + 6HCl (g)       ΔH = −755.4 kJWhat is ΔH per kilogram of diborane that reacts?
Hydrazine, N2H4, is a liquid used as a rocket fuel. It reacts with oxygen to yield nitrogen gas and water.N2H4 (l) + O2 (g) → N2 (g) + 2 H2O (l)The reaction of 6.50 g N2H4 evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted.
The combustion of hexane is given by the following reaction. 2C6H14 + 19O2 --> 12CO2 + 14H2O The enthalpy of reaction is -4163.0 kJ/mol. How much energy (in joules) will be released if 55.61 grams of hexane is burned. (Molar mass of hexane = 86.20 g/mol). Record your answer in scientific notation using 3 significant figures.
A gas mixture at 580.0°C and 113 kPa absolute enters a heat exchanger at a rate of 80.0 m3/hr. The gas leaves the heat exchanger at 150.0°C. The change in enthalpy of the gas during the cooling process is -7.00 kJ/mol. What is the heat required in kW? Assume the gas behaves ideally and that the changes in kinetic and potential energy are negligible.
Be sure to answer all parts.Stearic acid (C18H36O2) is a typical fatty acid, a molecule with a long hydrocarbon chain and an organic acid group (COOH) at the end. It is used to make cosmetics, ointments, soaps, and candles and is found in animal tissue as part of many saturated fats. In fact, when you eat meat, chances are that you are ingesting some fats that contain stearic acid. Calculate the heat (q) in kJ and kcal when 39.8 g of stearic acid is burned completely given that ΔH°f = -948 kJ/mol. 
Using the following equation for the combustion of octane, calculate the heat associated with the combustion of excess octane with 100.0 g of oxygen assuming complete combustion. The molar mass of octane is 114.33 g/mole. The molar mass of oxygen is 31.9988 g/mole.2 C8H18 + 25 O2 → 16 CO2 + 18 H2O            ΔH∘rxn = -11018 kJa. -1377 kJb. -4304 kJc. -11018 kJd. -2152 kJe. -17220 kJ
Consider the following thermochemical equation for the combustion of acetone (C3H4O), the main ingredient in nail polish remover. C3H6O(l) + 4 O2(g) --> 3CO2(g) + 3H2O(g) delta Hrxn = - 1790 kJIf a bottle of nail polish remover contains 178 mL of acetone, how much heat would be released by its complete combustion? The density of acetone is 0.788 g/mL.
How much heat in kilojoules is evolved or absorbed in each of the following reactions?Burning of 15.5 g of propane:C3H8(g) + 5 O2(g) → 3 CO2(g) + CO2(g) + 4H2O(l) ΔH°= -2220 kJReaction of 4.88 g of hydroxide with ammonium chloride.Ba(OH)2 •8H2O(s) + 2NH4Cl(s)→ BaCl2(aq) + 2 NH3(aq) + 10H2O(l) ΔH° = +80.3 kJ
If the heat of combustion for a specific compound is -1090.0 kJ/mol and its molar mass is 48.47 g/mol, how many grams of this compound must you burn to release 630.80 kJ of heat?
How much heat energy is required to boil 30.5 g of ammonia, NH3? The molar heat of vaporization of ammonia is 23.4 kJ/mol. 
The following thermochemical equation is for the reaction of bromine trifluoride(g) to form bromine(g) and fluorine(g). 2BrF3 (g) → Br2 (g) + 3F2 (g)       ΔH = 542 kJ How many grams of BrF3 (g) would be made to react if 95.7 kJ of energy were provided?
Enter your answer in the provided box.Liquid methanol (CH3OH) can be used as an alternative fuel in pickup and SUV engines. An industrial method for preparing it uses the catalytic hydrogenation of carbon monoxide: CO (g) + 2H2 (g) → CH3OH (l) How much heat (in kJ) is released when 15.0 L of CO at 85°C and 112 kPa reacts with 12.9 L of H 2 at 75°C and 744 torr?
The reaction of cyanamide, NH2CN(s), with oxygen was run in a bomb calorimeter, and ΔE was found to be -742.7 kJ/mol of NH2CN(s) at 298 K. Calculate ΔH for the reaction at this temperature. Reaction: NH2CN (s) + 3/2O2 (g) → N2 (g) + CO2 (g) + H2O (l) a. -727.8 kJ/mol b. -737.7 kJ c. -741.5 kJ d. -742.7 kJ e. none of the above
A chemist measures the energy change ΔH during the following reaction: CH4 (g)+2O2 (g) → CO2 (g) + 2H2O (l)     ΔH = -882. kJUse the information to answer the following questions. The reaction is:                   (i) endothermic.                    (ii) exothermic. Suppose 84.2 g of CH4 react. Will any heat be released or absorbed?                   (i) Yes, absorbed.                    (ii) Yes, released.                    (iii) No. If you said heat will be released or absorbed in the second part of this question, calculate how much heat in kJ will be released or absorbed. Round your answer to 3 significant digits.
When a 2.050 gram sample of methanol (CH3OH) was burned in air, it released 40.81 kilojoules (kJ) of heat. Calculate the enthalpy change for the combustion of exactly 1 mole of methanol. 
When a 5.00-g sample of KCI is dissolved in water in a calorimeter that has a total heat capacity of 2.683 kJ • K-1, the temperature decreases by 0.430 K. Calculate the molar heat of solution of KCI.
Using the following thermochemical equation, determine the amount of heat produced from the combustion of 24.3 g benzene (C6H6). The molar mass of benzene is 78.11 g/mole. 2 C6H6(l) + 15 O2(g) → 12 CO2(g) + 6 H2O(g)              ΔH°rxn = -6278 kJa. 40.1 kJb. 3910 kJc. 977 kJd. 0.302 kJe. 1950 kJ
Calcium oxide and water react in an exothermic reaction:CaO(s) + H2O(l) → Ca(OH)2(s)       Heat of reaction (Rxn) = -64.8 kJ/molHow much heat would be liberated when 7.15 g CaO(s) is dropped into a beaker containing 152 g H2O.a. 1.97 x 103 kJb. 508 kJc. 8.26 kJd. 547 kJe. 555 kJ
The oxidation of copper (l) oxide, Cu 2O(s), to copper(II) oxide, CuO(s), is an exothermic process, 2Cu2O(s) + O2(g) → 4CuO(s)                    ΔH°rxn = -292.0 kJ/mol Calculate the energy released as heat (kJ) when 50.05 g of Cu 2O(s) undergo oxidation at constant pressure.
The reaction for the combustion of propane is shown below. C3H8(g) + 5 O2 (g) → 3 CO2 (g)  + 4 H2O (l)    ΔH = - 526.3 kcal/molHow much heat is  released when 71.7 g of propane is burned? 
When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+ (ag) + Cl - (aq) → AgCI(s)       Δ H = - 65.5 kJ a) Calculate ΔH (kJ) for formation of 0.430 mol of AgCl by this reaction.  b) Calculate ΔH (kJ) for the formation of 6.00 g of AgCl.c) Calculate ΔH (J) when 9.23 x 10-4 mol of AgCI dissolves in water.