Question 1

Calculate the work,w,gained or lost by the system when a gas expands from 15 L to 40 L against a constant external pressure of 1.5199 bar.

Accepted Answer

A)  -6.1 kJ
B)  -3.8 kJ
C)  +3.8 kJ
D)  +6.1 kJ

Question 2

From the following thermochemical equations,calculate ΔrH° for the reaction:
SO2(g) + NO2(g) → SO3(g) + NO(g) 
2 SO2(g) + O2(g) → 2 SO3(g) ΔrH° = -197.8 kJ/mol
2 NO(g) + O2(g) → 2 NO2(g) ΔrH° = -114.14 kJ/mol

Accepted Answer

A)  -83.66 kJ /mol
B)  -311.9 kJ/mol
C)  +155.9 kJ/mol
D)  -155.9 kJ/mol
E)  -41.83 kJ/mol

Question 3

Given the heat of formation of the following compounds:
rH° for the reaction: CH3OH(l) + 3/2 O2(g) → CO2(g) + 2 H2O(l)  A) -440.8 kJ/mol B) -416.9 kJ/mol C) -1203.9 kJ/mol D) -346.2 kJ/mol E) -726.7 kJ/mol" class="answers-bank-image d-inline" rel="preload" >
What is the value of ΔrH° for the reaction:
CH3OH(l) + 3/2 O2(g) → CO2(g) + 2 H2O(l)

Accepted Answer

A)  -440.8 kJ/mol
B)  -416.9 kJ/mol
C)  -1203.9 kJ/mol
D)  -346.2 kJ/mol
E)  -726.7 kJ/mol

Question 4

The standard enthalpy of formation of NH4Cl(s) is -315.4 kJ/mol.The equation that describes this △fH° is:

Accepted Answer

A)  NH4+(aq) + Cl-(aq) → NH4Cl(s) 
B)  1/2 N2(g) + 2 H2(g) + 1/2 Cl2(g) → NH4Cl(s) 
C)  N2(g) + H2(g) + Cl2(g) → 2 NH4Cl(s) 
D)  1/2 N2(g) + 1/2 Cl2(g) + 1/2 H2(g) → NH4Cl(s) 
E)  N2(g) + Cl2(g) + 4 H2(g) → 2 NH4Cl(s)

Question 5

Coal contains an impurity that reacts with oxygen during the combustion process,producing oxides that are major environmental pollutants.This impurity is:

Accepted Answer

A)  acid rain
B)  nitrogen
C)  sulfur
D)  carbon dioxide
E)  peat

Question 6

Choose the INCORRECT statement.

Accepted Answer

A)  Kinetic energy is the energy of motion.
B)  Potential energy is energy in action.
C)  Heat is energy transferred as a result of a temperature difference.
D)  Pressure-volume work is calculated by w = −PΔV.
E)  Heat is transferred from a warmer body to a colder one.

Question 7

The complete combustion of propane,C3H8(g) ,is represented by the equation:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔrH° = -2220 kJ /mol
How much heat is evolved in the complete combustion of 12.5 L C3H8(g) at 25 °C and 790 mmHg?

Accepted Answer

A)  8.27 × 104 kJ
B)  1.41 × 104 kJ
C)  653 kJ
D)  168 kJ
E)  1180 kJ

Question 8

A 5.00 g sample of copper metal at 25.0 °C is heated by the addition of 96.0 J of energy.The final temperature of the copper is ________ °C.The specific heat capacity of copper is

Accepted Answer

A)  32.3
B)  25.0
C)  25.5
D)  75.5
E)  50.5

Question 9

Compute ΔrH° for the following reaction.The value of ΔfH° in kJ/mol is given below each species:
rH° for the following reaction.The value of ΔfH° in kJ/mol is given below each species:   A) -688.6 kJ/mol B) -200.1 kJ/mol C) -74.9 kJ/mol D) -1000.6 kJ/mol E) -900.3 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

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

Question 10

Consider the reaction: 
rH° for this reaction. A) -994.67 kJ/mol B) 23.05 kJ /mol C) -23.05 kJ /mol D) 69.25 kJ /mol E) -69.25 kJ/mol" class="answers-bank-image d-inline" rel="preload" >
Compute ΔrH° for this reaction.

Accepted Answer

A)  -994.67 kJ/mol
B)  23.05 kJ /mol
C)  -23.05 kJ /mol
D)  69.25 kJ /mol
E)  -69.25 kJ/mol

Question 11

Determine the enthalpy change in the following equation:
Cl2(g) + H2O(l) → 2 HCl(g) + 1/2 O2(g) 
ΔfH° H2O(l) = -285.8 kJ/mol
ΔfH° HCl(g) = -92.31 kJ/mol

Accepted Answer

A)  193.5 kJ/mol
B)  -470.4 kJ/mol
C)  470.4 kJ/mol
D)  101.2 kJ/mol
E)  -101.2 kJ/mol

Question 12

Calculate ΔfH° of octane,C8H18(l) ,given the enthalpy of combustion of octane to CO2(g) and H2O(l) ,-5471 kJ/mol,and the standard enthalpies of formation of CO2(g) and H2O(l) ,-393.5 kJ/mol and -285.8 kJ/mol,respectively.

Accepted Answer

A)  -249.2 kJ/mol
B)  +4792 kJ/mol
C)  +249.2 kJ/mol
D)  -4792 kJ/mol

Question 13

Oxygen gas at 34.5 °C expands from 34.5 L to 45.7 L against a constant pressure of 750 mmHg.What is the work done in joules by the system?

Accepted Answer

A)  1.12 × 103 J
B)  -1.12 × 103 J
C)  9.09 × 104 J
D)  -9.09 × 104 J
E)  4.55 × 103 J

Question 14

Kinetic energy is the energy of motion.

Accepted Answer

A) True 
 B)False

Question 15

A closed system can exchange matter but not energy with the surroundings.

Accepted Answer

A) True 
 B)False

Question 16

For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔrH° = -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

Question 17

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 bar 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

Question 18

The standard enthalpy for diamond and graphite are the same value.

Accepted Answer

A) True 
 B)False

Question 19

Calculate ΔU for a system that loses 475 kJ of heat and does 155 kJ of expansion work on the surroundings.

Accepted Answer

A)  -630 kJ
B)  -320 kJ
C)  +630 kJ
D)  +320 kJ

Question 20

The specific heat capacity of liquid mercury is 0.14 J g-1k-1.How many joules of heat are needed to raise the temperature of 5.00 g of mercury from 15.0 °C to 36.5 °C?

Accepted Answer

A)  7.7 × 102 J
B)  15 J
C)  36 J
D)  0.0013 J
E)  1.7 J

Exam 7: Thermochemistry

Given the heat of formation of the following compounds: What is the value of ΔrH° for the reaction: CH3OH(l) + 3/2 O2(g) → CO2(g) + 2 H2O(l)

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From the following thermochemical equations,calculate ΔrH° for the reaction: SO2(g) + NO2(g) → SO3(g) + NO(g) 2 SO2(g) + O2(g) → 2 SO3(g) ΔrH° = -197.8 kJ/mol 2 NO(g) + O2(g) → 2 NO2(g) ΔrH° = -114.14 kJ/mol

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The specific heat capacity of liquid mercury is 0.14 J g-1k-1.How many joules of heat are needed to raise the temperature of 5.00 g of mercury from 15.0 °C to 36.5 °C?

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The complete combustion of propane,C3H8(g) ,is represented by the equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔrH° = -2220 kJ /mol How much heat is evolved in the complete combustion of 12.5 L C3H8(g) at 25 °C and 790 mmHg?

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Calculate ΔfH° of octane,C8H18(l) ,given the enthalpy of combustion of octane to CO2(g) and H2O(l) ,-5471 kJ/mol,and the standard enthalpies of formation of CO2(g) and H2O(l) ,-393.5 kJ/mol and -285.8 kJ/mol,respectively.

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A closed system can exchange matter but not energy with the surroundings.

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Compute ΔrH° for the following reaction.The value of ΔfH° in kJ/mol is given below each species:

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Determine the enthalpy change in the following equation: Cl2(g) + H2O(l) → 2 HCl(g) + 1/2 O2(g) ΔfH° H2O(l) = -285.8 kJ/mol ΔfH° HCl(g) = -92.31 kJ/mol

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Choose the INCORRECT statement.

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Kinetic energy is the energy of motion.

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

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A 5.00 g sample of copper metal at 25.0 °C is heated by the addition of 96.0 J of energy.The final temperature of the copper is ________ °C.The specific heat capacity of copper is

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Coal contains an impurity that reacts with oxygen during the combustion process,producing oxides that are major environmental pollutants.This impurity is:

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The standard enthalpy for diamond and graphite are the same value.

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Calculate the work,w,gained or lost by the system when a gas expands from 15 L to 40 L against a constant external pressure of 1.5199 bar.

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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 bar of pressure IV.have a concentration of 1.0000 M

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The standard enthalpy of formation of NH4Cl(s) is -315.4 kJ/mol.The equation that describes this △fH° is:

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Consider the reaction: Compute ΔrH° for this reaction.

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Oxygen gas at 34.5 °C expands from 34.5 L to 45.7 L against a constant pressure of 750 mmHg.What is the work done in joules by the system?

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Calculate ΔU for a system that loses 475 kJ of heat and does 155 kJ of expansion work on the surroundings.

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Given the heat of formation of the following compounds: What is the value of Δ_rH° for the reaction: CH₃OH(l) + 3/2 O₂(g) → CO₂(g) + 2 H₂O(l)

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From the following thermochemical equations,calculate Δ_rH° for the reaction: SO₂(g) + NO₂(g) → SO₃(g) + NO(g) 2 SO₂(g) + O₂(g) → 2 SO₃(g) Δ_rH° = -197.8 kJ/mol 2 NO(g) + O₂(g) → 2 NO₂(g) Δ_rH° = -114.14 kJ/mol

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The specific heat capacity of liquid mercury is 0.14 J g^-1k^-1.How many joules of heat are needed to raise the temperature of 5.00 g of mercury from 15.0 °C to 36.5 °C?

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The complete combustion of propane,C₃H₈(g) ,is represented by the equation: C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(l) Δ_rH° = -2220 kJ /mol How much heat is evolved in the complete combustion of 12.5 L C₃H₈(g) at 25 °C and 790 mmHg?

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Calculate Δ_fH° of octane,C₈H₁₈(l) ,given the enthalpy of combustion of octane to CO₂(g) and H₂O(l) ,-5471 kJ/mol,and the standard enthalpies of formation of CO₂(g) and H₂O(l) ,-393.5 kJ/mol and -285.8 kJ/mol,respectively.

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Compute Δ_rH° for the following reaction.The value of Δ_fH° in kJ/mol is given below each species:

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Determine the enthalpy change in the following equation: Cl₂(g) + H₂O(l) → 2 HCl(g) + 1/2 O₂(g) Δ_fH° H₂O(l) = -285.8 kJ/mol Δ_fH° HCl(g) = -92.31 kJ/mol

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

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The standard enthalpy of formation of NH₄Cl(s) is -315.4 kJ/mol.The equation that describes this △_fH° is:

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Consider the reaction: Compute Δ_rH° for this reaction.

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