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Enthalpy of Formation Solutions Library

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Enthalpy of Formation

Q. For each of the following reactions, identify another quantity that is equal to Δ°Hrxn. 1. CH4(g) + 2O2(g) →CO2(g) + 2H2O(l) a) enathalpy of combus...

Solved • Mar 25, 2020

Enthalpy of Formation

Q. Calculate ΔH° for each of the following reactions, which occur in the atmosphere.(a) C2H4(g) + O3(g) → CH3CHO(g) + O2(g)(b) O3(g) + O(g) → 2 O2(g)

Solved • Mar 25, 2020

Enthalpy of Formation

Q. Calculate ΔH° for each of the following reactions, which occur in the atmosphere.(a) O3(g) + NO(g) → NO2(g) + O2(g)(b) SO3(g) + H2O(l) → H2SO4(aq)

Solved • Mar 25, 2020

Enthalpy of Formation

Q. A hypothetical solution forms between a solid and a liquid. The values of the thermodynamic quantities involved in the process are shown in the fol...

Solved • Mar 17, 2020

Enthalpy of Formation

Q. Estimate ΔH°rxn for the following reaction, using the chemical reactions given above and the ΔH°rxn values you calculated in part (a). Show all wor...

Solved • Dec 19, 2019

Enthalpy of Formation

Q. Estimate the enthalpy of reaction, ΔH rxn°, for each of the following reactions using the information provided. Show all work and circle your final...

Solved • Dec 19, 2019

Enthalpy of Formation

Q. Estimate the enthalpy of reaction, ΔH rxn°, for each of the following reactions using the information provided. Show all work and circle your final...

Solved • Dec 19, 2019

Enthalpy of Formation

Q. Estimate the enthalpy of reaction, ΔH rxn°, for each of the following reactions using the information provided. Show all work and circle your final...

Solved • Dec 19, 2019

Enthalpy of Formation

Q. Gaseous hydrogen and fluorine combine in the reaction below to form hydrogen fluoride:H2(g) + F2(g) → 2 HF(g)        ΔH°rxn = -540 kJWhat is the va...

Solved • Nov 25, 2019

Enthalpy of Formation

Q. The ΔHf° for CO2 (g) is -393 kJ/mole and ΔHrxn for the reaction2CO(g) + O2(g) → 2CO2(g) is -560 kJ. The ΔHf° for CO(g) is (in kJ/mole):(a) +113 (b)...

Solved • Oct 18, 2019

Enthalpy of Formation

Q. For the reaction,2H2 (g) + O2 (g) → 2H2O(g) ΔH = -484 kJwhich of the following is true?(a) The ΔHf° for H2O(g) is -484 kJ/mole.(b) All reactants an...

Solved • Oct 18, 2019

Enthalpy of Formation

Q. What is ΔHrxn at 25C?ΔHf ° (H+) = 0.0 kJ/mol;ΔHf ° (OH-) = -230.0 kJ/mol;ΔHf ° (H2O) = -285.8 kJ/mol)H+ (aq) + OH- (aq) → H2O (l)A. -55.8 J/mol B. ...

Solved • Oct 9, 2019

Enthalpy of Formation

Q. For which of the following reactions is the value of ∆H°rxn equal to ∆H°f for the product?I. N2(g) + O3(g) ⟶ N2O3(g)II. 2 Ca(s) + O2(g) ⟶ 2 CaO(s)I...

Solved • Oct 3, 2019

Enthalpy of Formation

Q. Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l):2 B5H9(s) + 12 O2(g) ⟶5 B2O3(s) + 9 H2O(l)The standard enthalpy change for th...

Solved • Oct 3, 2019

Enthalpy of Formation

Q. Given the data in the table below, ΔH°rxn for the following reaction is __________ kJ.3NO2(g) + H2O(l) → 2HNO3 (aq) + NO (g)A) 64B) 140C) -140D) -5...

Solved • Sep 24, 2019

Enthalpy of Formation

Q. For which one of the following equations is ΔH°rxn equal to ΔHf° for the product?A) Xe(g) + 2F2(g) → XeF4 (g)B) CH4(g) + 2Cl2(g) → CH2Cl2(l) + 2HCl...

Solved • Sep 24, 2019

Enthalpy of Formation

Q. The value of ΔH° for the reaction below is +128.1 kJ:CH3OH(l) → CO(g) + 2H2(g)How many kJ of heat are consumed when 5.10 g of CO(g) is formed as sh...

Solved • Sep 24, 2019

Enthalpy of Formation

Q. Consider the following reaction:2Mg(s) + O2(g)→ 2MgO(s)        ΔH = -1204 kJWhich of the following statements is true?a) This reaction is endotherm...

Solved • Sep 15, 2019

Enthalpy of Formation

Q. Given the data in the table on the right, the ΔH°rxn for the reaction:Ca(OH)2 + 2 H3AsO4 → Ca(H2AsO4)2 + 2 H2O  is ___________ kJ.A. -744.9B. -4519...

Solved • Sep 13, 2019

Enthalpy of Formation

Q. The value of ΔH° for the reaction below is -790 kJ. The enthalpy change accompanying the reaction of 0.95 g of S is __________ kJ.                 ...

Solved • Sep 13, 2019

Enthalpy of Formation

Q. Calculate the enthalpy change (ΔH) for the following reaction:H2(g) + F2(g) = 2HF

Solved • Aug 25, 2019

Enthalpy of Formation

Q. For which of the following reactions is ΔH°rxn equal to ΔH°f of the product(s)?2Na(s) + Cl2(g) → 2NaCl(s)H2(g) + 12O2(g) → H2O(g)Na(s) + 12Cl2(g) →...

Solved • Aug 7, 2019

Enthalpy of Formation

Q. What is ΔHrxn° for the following chemical reaction? CS2(g) + 2H2O(l) → CO2(g) + 2H2S(g) You can use the following table of standard heats of format...

Solved • Aug 6, 2019

Enthalpy of Formation

Q. Use the information in the table to calculate ΔH° in kilojoules for the photosynthesis of glucose (C6H12O6) and O2 from CO2 and liquid H2O, a react...

Solved • Aug 6, 2019

Enthalpy of Formation

Q. Part A. Calculate the enthalpy change, delta H, for the expansion of methaneCH4(g) → C(g) + 4H(g)Part B. Calculate the enthalpy change, delta H for...

Solved • Jul 10, 2019

Enthalpy of Formation

Q. The standard enthalpy of combustion of naphthalene is -5157 kJ/mol. Calculate its standard enthalpy of formation.The reaction for the combustion of...

Solved • Jul 9, 2019

Enthalpy of Formation

Q. The fuel in high-efficiency natural gas vehicles consists primarily of methane CH4.How much heat is produced in burning 6 mol of CH4 under standard...

Solved • Jan 3, 2019

Enthalpy of Formation

Q. Consider the following equilibrium between oxides of nitrogen: 3NO(g) ⇌ NO2(g) + N2O(g)Use data in Appendix C in the textbook to calculate ΔH˚ for ...

Solved • Dec 11, 2018

Enthalpy of Formation

Q. Methanol (CH3OH) can be made by the reaction of CO with H2: CO(g) + 2 H2(g) ⇌ CH3OH(g)Use thermochemical data in Appendix C in the textbook to calc...

Solved • Dec 11, 2018

Enthalpy of Formation

Q. Acetylene (C2H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their chemical properties.Both N2 and C2H2 possess triple...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Acetylene (C2H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their chemical properties.Calculate the enthalpy of oxida...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Estimate ΔH for the atomization of benzene, C6H6: C6H6(g) → 6 C(g) + 6 H(g), by using ΔH˚f data (ΔH˚f (C, g) = 718.4 kJ/mol, ΔH˚f (H, g) = 217.94 k...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. The stratospheric ozone (O3) layer helps to protect us from harmful ultraviolet radiation. It does so by absorbing ultraviolet light and falling ap...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Consider the decomposition of liquid hydrogen peroxide (H2O2) to form water and oxygen.What is the heat of formation for gaseous oxygen?

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Consider the decomposition of liquid hydrogen peroxide (H2O2) to form water and oxygen. Write the balanced chemical equation that corresponds to th...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Consider the decomposition of liquid hydrogen peroxide (H2O2) to form water and oxygen. Write the balanced chemical equation that corresponds to th...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Pentane (C5H12) is a component of gasoline that burns according to the following balanced equation: C5H12(l) + 8 O2(g) → 5 CO2(g) + 6 H2O(g). Calcu...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation of Fe2O3 (s) from its elements in their standard states.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation of CH4 (g) from its elements in their standard states.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation of one mole of NO2 (g) from its elements in their standard states.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation one mole of MgCO3 (s) from its elements in their standard states. Write any reference to carbon as C(s).

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation one mole of C2H4 (g) from its elements in their standard states. Write any reference to carbon as C(s).

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation one mole of CH3OH(l) from its elements in their standard states. Write any reference to carbon as C(s).

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the equation: CO2(s) → CO2(g). When dry ice is adde...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation of NH3 (g) from its elements in their standard states.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Write an equation for the formation of CO2 (g) from its elements in their standard states.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. The standard enthalpy of formation for glucose, C6H12O6(s), is –1273.3 kJ/mol. What is the correct formation equation corresponding to this ΔH˚f?

Solved • Nov 12, 2018

Enthalpy of Formation

Q. When backpacking in the wilderness, hikers often boil water to sterilize it for drinking. Suppose that you are planning a backpacking trip and will...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. When 10.00 g of phosphorus is burned in O2(g) to form P4O10(s), enough heat is generated to raise the temperature of 2960 g of water from 18.0˚C to...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Palmitic acid (C16H32O2) is a dietary fat found in beef and butter. The caloric content of palmitic acid is typical of fats in general. Calculate t...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Calculate the standard enthalpy of combustion of sucrose. The standard enthalpy of formation of sucrose is –2226.1kJ/mol.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Hydrogen and methanol have both been proposed as alternatives to hydrocarbon fuels. Use standard enthalpies of formation to calculate the amount of...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Hydrogen and methanol have both been proposed as alternatives to hydrocarbon fuels. To compare the energy of these fuels to that of octane (C8H18),...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Hydrogen and methanol have both been proposed as alternatives to hydrocarbon fuels. Use standard enthalpies of formation to calculate the amount of...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Under certain nonstandard conditions, oxidation by O2(g) of 1 mol of SO2(g) to SO3(g) absorbs 89.6 kJ. The heat of formation of SO3(g) is –204.1 kJ...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. During photosynthesis, plants use energy from sunlight to form glucose, C6H12O6(s), and oxygen from carbon dioxide and water. Calculate ΔH˚rxn for ...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Ethanol can be made from the fermentation of crops and has been used as a fuel additive to gasoline. Calculate ΔH˚rxn for the combustion of ethanol.

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Top fuel dragsters and funny cars burn nitromethane as fuel according to the following balanced combustion equation: 2 CH3NO2(l) + 3/2 O2(g) → 2 CO...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Methanol (CH3 OH) has been suggested as a fuel to replace gasoline. Write a balanced equation for the combustion of methanol, find ΔH˚rxn, and dete...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Hydrazine (N2H4) is a fuel used by some spacecraft. It is normally oxidized by N2O4 according to the following equation: N2H4(l) + N2O4(g) → 2 N2O(...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Use standard enthalpies of formation to calculate ΔH˚rxn for the following reaction: Cr2O3(s) + 3 CO(g) → 2 Cr(s) + 3 CO2(g){ m{Cr}}_2 { m{O}}_3 (s...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. The table below shows the average bond energies for some common bonds among carbon, hydrogen, and oxygen.BondBond energy(kJ/mol)C - C347C - H414C -...

Solved • Nov 12, 2018

Enthalpy of Formation

Q. Consider the reaction: H2(g) + I2(s) → 2 HI(g)Use the enthalpies of formation in Appendix C to determine the true reaction enthalpy.

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Which is more stable at room temperature, a Cl2 molecule or two separate Cl atoms?

Solved • Oct 31, 2018

Enthalpy of Formation

Q. What is the energy difference between the Cl2 molecule and the separated atoms?

Solved • Oct 31, 2018

Enthalpy of Formation

Q. First launch the video. The video will show you the Smart Figure. After watching the video, answer the related follow-up question. You can watch th...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Use bond enthalpies in the table below to estimate ΔH for each of the following reactions.Average Bond Enthalpies (kJ/mol)C-H 413N-H 391O-H 463F-F ...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. The standard enthalpies of formation of gaseous propyne (C3H4), propylene (C3H6), and propane (C3H8) are +185.4, +20.4, and -103.8 kJ/mol, respecti...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Consider the two diagrams below.Based on (i), write an equation showing how HA is related to HB and HC.

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Write the chemical equation for the reaction whose enthalpy change is the standard enthalpy of formation of sucrose, C12H22O11(s), HfHf[{ m C_{12}H...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. A gas-phase reaction was run in an apparatus designed to maintain a constant pressure.Using data from Appendix C in the textbook, determine H for t...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. 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.Choose an enth...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Thermodynamic Quantities for Selected Substances at 298.15 KSubstanceΔH˚f (kJ/mol)NO(g)90.37NO2(g)33.84N2O(g)81.6N2O4(g)9.66SO2(g)-296.9SO3(g)-395....

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Thermodynamic Quantities for Selected Substances at 298.15 KSubstanceHfo (kJ/mol)NO(g)90.37NO2(g)33.84N2O(g)81.6N2O4(g)9.66SO2(g)-296.9SO3(g)-395.2...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Write a balanced chemical equation depicting the formation of one mole of CaCO3(s) from its elements in their standard states.

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Write a balanced chemical equation depicting the formation of one mole of POCl3(l) from its elements in their standard states.

Solved • Oct 31, 2018

Enthalpy of Formation

Q. For H2O2(g), find the value of Hf. (Use Appendix C in the textbook.)

Solved • Oct 31, 2018

Enthalpy of Formation

Q. For CaCO3(s), find the value of Hf. (Use Appendix C in the textbook.)

Solved • Oct 31, 2018

Enthalpy of Formation

Q. For POCl3(l), find the value of Hf. (Use Appendix C in the textbook.)

Solved • Oct 31, 2018

Enthalpy of Formation

Q. For C2H5OH(l), find the value of Hf. (Use Appendix C in the textbook.)

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Diethyl ether, C4H10O (l), a flammable compound that has long been used as a surgical anesthetic, has the structureCH3 - CH2 - O - CH2 - CH3The com...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. The complete combustion of ethanol, C2H5OH (l), to form H2O (g) and CO2 (g) at constant pressure releases 1235 kJ of heat per mole of C2H5OH.Write ...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. 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 H2...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. The metathesis reaction between AgNO3 (aq) and NaCl(aq) proceeds as follows: AgNO3(aq) + NaCl(aq) → NaNO3(aq) + AgCl(s)By using Appendix C in the t...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. The hydrocarbons acetylene (C2H2) and benzene (C6H6) have the same empirical formula. Benzene is an "aromatic" hydrocarbon, one that is unusually s...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. The hydrocarbons acetylene (C2 H2 ) and benzene (C6 H6 ) have the same empirical formula. Benzene is an "aromatic" hydrocarbon, one that is unusual...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Ozone, O3(g), is a form of elemental oxygen produced during electrical discharge. Is ΔH˚f(g) for O3(g) necessarily zero?

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Ethanol (C2H5OH) is currently blended with gasoline as an automobile fuel.Calculate the standard enthalpy change for the reaction, assuming H2O(g) ...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. You may want to reference (Pages 187 - 190) Section 5.7 while completing this problem.Using values from Appendix C, calculate the value of ΔH˚ for ...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. What is meant by the term standard conditions, with reference to enthalpy changes?

Solved • Oct 31, 2018

Enthalpy of Formation

Q. The following is known as the thermite reaction: 2 Al(s) + Fe2O3(s) → Al2O3 (s) + 2 Fe(s)This highly exothermic reaction is used for welding massiv...

Solved • Oct 31, 2018

Enthalpy of Formation

Q. Ethanol (CH3CH2OH) is being used as a gasoline additive or alternative in many parts of the world.(a) Use bond energies to find ΔH°rxn for the comb...

Solved • Oct 28, 2018

Enthalpy of Formation

Q. Calculate ΔH° for each of the following reactions, which occur in the atmosphere.a. C2H4 (g) + O3 (g) → CH3CHO (g) + O2 (g)

Solved • Oct 19, 2018

Enthalpy of Formation

Q. Calculate ΔH° for each of the following reactions, which occur in the atmosphere.c. SO3 (g) + H2O (l) → H2SO4 (aq)

Solved • Oct 19, 2018

Enthalpy of Formation

Q. At 298 K, the standard enthalpies of formation for C2H2(g) and C6H6(l) are 227 kJ/mol and 49 kJ/mol, respectively. a. Calculate ΔH° forC6H6 (l) → 3...

Solved • Oct 19, 2018

Enthalpy of Formation

Q. Some automobiles and buses have been equipped to burn propane (C3H8). Compare the amounts of energy that can be obtained per gram of C3H8(g) and pe...

Solved • Oct 18, 2018

Enthalpy of Formation

Q. Water gas is produced from the reaction of steam with coal:C(s) + H2O (g) → H2 (g) + CO (g)Assuming that coal is pure graphite, calculate ΔH° for t...

Solved • Oct 18, 2018

Enthalpy of Formation

Q. The standard enthalpy of combustion of ethene gas, C2H4(g), is -1411.1 kJ/mol at 298 K. Given the following enthalpies of formation, calculate ΔHf°...

Solved • Oct 18, 2018

Enthalpy of Formation

Q. The Ostwald process for the commercial production of nitric acid from ammonia and oxygen involves the following steps:4NH3 (g) + 5O2 (g) → 4NO (g) ...

Solved • Oct 18, 2018

Enthalpy of Formation

Q. Use the values of ΔHf° to calculate ΔH° for the following reactionsΔHf for C2H5OH (l) is -278 kJ/mol; H2O (g) is -242 kJ/mol; CO2 (g) is -393.5 kJ/mol

Solved • Oct 18, 2018