Question 1

The heat of combustion of methane is -50.38 kJ/mol. How many moles of methane must be burned to produce 137 kJ of heat?

Accepted Answer

A)  6.90 mol 
B)  0.367 mol 
C)  2.72 mol 
D)  1.37 mol 
E)  0.272 mol 
A)  6.90 mol 
B)  0.367 mol 
C)  2.72 mol 
D)  1.37 mol 
E)  0.272 mol

Question 2

A certain reaction releases 10.1 kJ at constant volume and at constant pressure releases 8.4 kJ. What is △U for the reaction?

Accepted Answer

A)  -10.1 kJ 
B)  -8.4 kJ 
C)  +8.4 kJ 
D)  -1.7 kJ 
A)  -10.1 kJ 
B)  -8.4 kJ 
C)  +8.4 kJ 
D)  -1.7 kJ

Question 3

The standard heat of formation of solid ammonium bromide is -270.8 kJ/mol. Write the chemical equation for the reaction to which this value applies.

Accepted Answer

@#IMG-DLM& N₂(g) + 2

Question 4

The heat of combustion of several fuels are listed in the table below. On a per gram basis, which fuel releases the most energy?

Accepted Answer

A)  C(s) 
B)  CH4(g) 
C)  CH3OH(l) 
D)  C3H8(g) 
E)  H2(g) 
A)  C(s) 
B)  CH4(g) 
C)  CH3OH(l) 
D)  C3H8(g) 
E)  H2(g)

Question 5

100.0 g of Cu (specific heat = 0.385 J/g °C) at 100.0°C is added to 140.0 mL of H2O (specific heat = 4.184 J/g °C) at 25.0°C. What is the final temperature of the mixture?

Accepted Answer

A)  56.3 °C 
B)  29.6 °C 
C)  62.5 °C 
D)  91.4 °C 
E)  33.7 °C 
A)  56.3 °C 
B)  29.6 °C 
C)  62.5 °C 
D)  91.4 °C 
E)  33.7 °C

Question 6

The final temperature when 150 mL of water at 90.0°C is added to 100.0 mL of water at 30.0°C is around ________.

Accepted Answer

A)  90 °C 
B)  120 °C 
C)  30 °C 
D)  60 °C 
E)  25 °C 
A)  90 °C 
B)  120 °C 
C)  30 °C 
D)  60 °C 
E)  25 °C

Question 7

Lead, water, sulfur, and arsenic have specific heats of 0.128, 4.18, 0.706, and 0.329 J g-1°C-1, respectively. Which of the following would need the smallest quantity of heat to change the temperature of 5 g by 10°C?

Accepted Answer

A)  lead 
B)  water 
C)  sulfur 
D)  arsenic 
A)  lead 
B)  water 
C)  sulfur 
D)  arsenic

Question 8

What is the final temperature in the bomb calorimeter if 1.785 grams of benzoic acid (HC7H5O2) is combusted in a calorimeter with a heat capacity of 5.02 kJ/°C and initial temperature of 24.62 °C? The heat of combustion of benzoic acid is -26.42 kJ/g.

Accepted Answer

A)  51.0°C 
B)  29.8°C 
C)  31.2°C 
D)  15.5°C 
E)  33.7°C 
A)  51.0°C 
B)  29.8°C 
C)  31.2°C 
D)  15.5°C 
E)  33.7°C

Question 9

For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔH° = -241.8 kJ/mol, what mass of H2(g) is required to liberate 1.00 × 103 kJ of heat?

Accepted Answer

A)  66.2 g 
B)  4.17 g 
C)  8.34 g 
D)  2.05 g 
E)  16.7 g 
A)  66.2 g 
B)  4.17 g 
C)  8.34 g 
D)  2.05 g 
E)  16.7 g

Question 10

The complete combustion of propane, C3H8(g), is represented by the equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ
How much heat is evolved in the complete combustion of 20.0 L C3H8(g) at STP?

Accepted Answer

A)  2486 kJ 
B)  1007 kJ 
C)  994 kJ 
D)  1982 kJ 
E)  495 kJ 
A)  2486 kJ 
B)  1007 kJ 
C)  994 kJ 
D)  1982 kJ 
E)  495 kJ

Question 11

The standard enthalpy of formation for CuSO4 ∙ 5H2O(s) is -2278.0 kJ/mole at 25°C. The chemical equation to which this value applies is:

Accepted Answer

A)  Cu(s) + S(s) + 5 H2O(g) + 2 O2(g) → CuSO4 ∙ 5H2O(s) 
B)  Cu(s) + S(s) + 9/2 O2(g) + 5 H2(g) → CuSO4 ∙ 5H2O(s) 
C)  Cu(s) + SO4(g) + 5 H2O(g) → CuSO4 ∙ 5H2O(s) 
D)  Cu(s) + S(s) + 5/9 O2(g) + 5 H2(g) → CuSO4 ∙ 5H2O(s) 
E)  2Cu(s) + 2 SO2(g) + 5 H2O(g) → 2CuSO4 ∙ 5H2O(s) 
A)  Cu(s) + S(s) + 5 H2O(g) + 2 O2(g) → CuSO4 ∙ 5H2O(s) 
B)  Cu(s) + S(s) + 9/2 O2(g) + 5 H2(g) → CuSO4 ∙ 5H2O(s) 
C)  Cu(s) + SO4(g) + 5 H2O(g) → CuSO4 ∙ 5H2O(s) 
D)  Cu(s) + S(s) + 5/9 O2(g) + 5 H2(g) → CuSO4 ∙ 5H2O(s) 
E)  2Cu(s) + 2 SO2(g) + 5 H2O(g) → 2CuSO4 ∙ 5H2O(s)

Question 12

The maximum amount of work is provided by a reversible process because equilibrium between the system and the surroundings is always maintained.

Accepted Answer

A) True 
 B)False

Question 13

Cyclohexanol, C6H12O, has a heat of combustion of -890.7 kcal/mol. A sample containing only 0.708 g of cyclohexanol undergoes complete combustion in a bomb calorimeter that has a heat capacity of 2.70 kcal/°C. What is the final temperature if the initial water temperature is 27.0°C?

Accepted Answer

A)  24.7 °C 
B)  29.3 °C 
C)  27.4 °C 
D)  26.6 °C 
E)  31.4 °C 
A)  24.7 °C 
B)  29.3 °C 
C)  27.4 °C 
D)  26.6 °C 
E)  31.4 °C

Question 14

The standard enthalpy of formation of NiSO4(s) at 25 °C is -872.9 kJ/mole. The chemical equation to which this value applies is:

Accepted Answer

A)  1/2 Ni(s) + 1/2 S(s) + 1/2 O2(g) → 1/2 NiSO4(s) 
B)  Ni(s) + S(s) + 4 O(g) → NiSO4(s) 
C)  Ni(s) + S(s) + 2 O2(g) → NiSO4(s) 
D)  Ni(s) + 1/8 S8(s) + 1/2 O2(g) → NiSO4(s) 
E)  NiSO4(s) → Ni(s) + S(s) + 4 O(g) 
A)  1/2 Ni(s) + 1/2 S(s) + 1/2 O2(g) → 1/2 NiSO4(s) 
B)  Ni(s) + S(s) + 4 O(g) → NiSO4(s) 
C)  Ni(s) + S(s) + 2 O2(g) → NiSO4(s) 
D)  Ni(s) + 1/8 S8(s) + 1/2 O2(g) → NiSO4(s) 
E)  NiSO4(s) → Ni(s) + S(s) + 4 O(g)

Question 15

What is the enthalpy of reaction for the neutralization reaction occurring between dilute Ba(OH)2(aq) and dilute HNO3(aq)? Values of ΔH°f from data tables are given below. Hint: Balance the equation so the coefficients are the lowest possible set of whole numbers.

Accepted Answer

A)  +426.0 kJ 
B)  -111.6 kJ 
C)  -426.0 kJ 
D)  -571.6 kJ 
E)  -460.0 kJ 
A)  +426.0 kJ 
B)  -111.6 kJ 
C)  -426.0 kJ 
D)  -571.6 kJ 
E)  -460.0 kJ

Question 16

To have a standard enthalpy of formation referenced to 0 J/mol, the substance must: I) be a simple substance (chemical element)
II) be in its most stable form
III) be under 1 atm of pressure
IV) have a concentration of 1.0000 M

Accepted Answer

A)  I, III, IV 
B)  I, II, III 
C)  II, IV 
D)  I, III 
E)  II, III, IV 
A)  I, III, IV 
B)  I, II, III 
C)  II, IV 
D)  I, III 
E)  II, III, IV

Question 17

Compute ΔH°rxn for the following reaction. The value of ΔH°f in kJ/mol is given below each species: 
PCl5(g) + 4 H2O(l) → H3PO4(s) + 5 HCl(g)
-398.9&emsp; -285.9&emsp;  &emsp;-1281.1&emsp; &emsp;&emsp;-92.30

Accepted Answer

A)  -688.6 kJ 
B)  -200.1 kJ 
C)  -74.9 kJ 
D)  -1000.6 kJ 
E)  -900.3 kJ 
A)  -688.6 kJ 
B)  -200.1 kJ 
C)  -74.9 kJ 
D)  -1000.6 kJ 
E)  -900.3 kJ

Question 18

An expansion of gas by a system means that the internal energy of the system increases.

Accepted Answer

A) True 
 B)False

Question 19

Calculate the amount of heat absorbed by a 40.0 g sample of water at 21°C when the temperature is raised to 35°C.

Accepted Answer

A)  5.9 kJ 
B)  -0.56 kJ 
C)  0.56 kJ 
D)  -2.3 kJ 
E)  2.3 kJ 
A)  5.9 kJ 
B)  -0.56 kJ 
C)  0.56 kJ 
D)  -2.3 kJ 
E)  2.3 kJ

Question 20

Enthalpy is an extensive property.

Accepted Answer

A) True 
 B)False

Exam 7: Thermochemistry

The heat of combustion of methane is -50.38 kJ/mol. How many moles of methane must be burned to produce 137 kJ of heat?

A certain reaction releases 10.1 kJ at constant volume and at constant pressure releases 8.4 kJ. What is △U for the reaction?

The standard heat of formation of solid ammonium bromide is -270.8 kJ/mol. Write the chemical equation for the reaction to which this value applies.

The heat of combustion of several fuels are listed in the table below. On a per gram basis, which fuel releases the most energy?

100.0 g of Cu (specific heat = 0.385 J/g °C) at 100.0°C is added to 140.0 mL of H2O (specific heat = 4.184 J/g °C) at 25.0°C. What is the final temperature of the mixture?

The final temperature when 150 mL of water at 90.0°C is added to 100.0 mL of water at 30.0°C is around ________.

Lead, water, sulfur, and arsenic have specific heats of 0.128, 4.18, 0.706, and 0.329 J g-1°C-1, respectively. Which of the following would need the smallest quantity of heat to change the temperature of 5 g by 10°C?

What is the final temperature in the bomb calorimeter if 1.785 grams of benzoic acid (HC7H5O2) is combusted in a calorimeter with a heat capacity of 5.02 kJ/°C and initial temperature of 24.62 °C? The heat of combustion of benzoic acid is -26.42 kJ/g.

For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔH° = -241.8 kJ/mol, what mass of H2(g) is required to liberate 1.00 × 103 kJ of heat?

The complete combustion of propane, C3H8(g), is represented by the equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ How much heat is evolved in the complete combustion of 20.0 L C3H8(g) at STP?

The standard enthalpy of formation for CuSO4 ∙ 5H2O(s) is -2278.0 kJ/mole at 25°C. The chemical equation to which this value applies is:

The maximum amount of work is provided by a reversible process because equilibrium between the system and the surroundings is always maintained.

Cyclohexanol, C6H12O, has a heat of combustion of -890.7 kcal/mol. A sample containing only 0.708 g of cyclohexanol undergoes complete combustion in a bomb calorimeter that has a heat capacity of 2.70 kcal/°C. What is the final temperature if the initial water temperature is 27.0°C?

The standard enthalpy of formation of NiSO4(s) at 25 °C is -872.9 kJ/mole. The chemical equation to which this value applies is:

What is the enthalpy of reaction for the neutralization reaction occurring between dilute Ba(OH)2(aq) and dilute HNO3(aq)? Values of ΔH°f from data tables are given below. Hint: Balance the equation so the coefficients are the lowest possible set of whole numbers.

To have a standard enthalpy of formation referenced to 0 J/mol, the substance must: I) be a simple substance (chemical element) II) be in its most stable form III) be under 1 atm of pressure IV) have a concentration of 1.0000 M

Compute ΔH°rxn for the following reaction. The value of ΔH°f in kJ/mol is given below each species: PCl5(g) + 4 H2O(l) → H3PO4(s) + 5 HCl(g) -398.9 -285.9 -1281.1 -92.30

An expansion of gas by a system means that the internal energy of the system increases.

Calculate the amount of heat absorbed by a 40.0 g sample of water at 21°C when the temperature is raised to 35°C.

Enthalpy is an extensive property.

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Chemical Kinetics

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

Electrochemistry

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

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100.0 g of Cu (specific heat = 0.385 J/g °C) at 100.0°C is added to 140.0 mL of H₂O (specific heat = 4.184 J/g °C) at 25.0°C. What is the final temperature of the mixture?

What is the final temperature in the bomb calorimeter if 1.785 grams of benzoic acid (HC₇H₅O₂) is combusted in a calorimeter with a heat capacity of 5.02 kJ/°C and initial temperature of 24.62 °C? The heat of combustion of benzoic acid is -26.42 kJ/g.

For the reaction H₂(g) + 1/2 O₂(g) → H₂O(g) ΔH° = -241.8 kJ/mol, what mass of H₂(g) is required to liberate 1.00 × 10³ kJ of heat?

The complete combustion of propane, C₃H₈(g), is represented by the equation: C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(l) ΔH° = -2220 kJ How much heat is evolved in the complete combustion of 20.0 L C₃H₈(g) at STP?

The standard enthalpy of formation for CuSO₄ ∙ 5H₂O(s) is -2278.0 kJ/mole at 25°C. The chemical equation to which this value applies is:

Cyclohexanol, C₆H₁₂O, has a heat of combustion of -890.7 kcal/mol. A sample containing only 0.708 g of cyclohexanol undergoes complete combustion in a bomb calorimeter that has a heat capacity of 2.70 kcal/°C. What is the final temperature if the initial water temperature is 27.0°C?

The standard enthalpy of formation of NiSO₄(s) at 25 °C is -872.9 kJ/mole. The chemical equation to which this value applies is:

What is the enthalpy of reaction for the neutralization reaction occurring between dilute Ba(OH)₂(aq) and dilute HNO₃(aq)? Values of ΔH°f from data tables are given below. Hint: Balance the equation so the coefficients are the lowest possible set of whole numbers.

Compute ΔH°rxn for the following reaction. The value of ΔH°f in kJ/mol is given below each species: PCl₅(g) + 4 H₂O(l) → H₃PO₄(s) + 5 HCl(g) -398.9 -285.9 -1281.1 -92.30