Question 1

A 2.38 g sample of phenol (C6H6O, molar mass = 94.11 g mol-1) was combusted in a bomb calorimeter with a heat capacity of 6.65 kJ °C-1. If the temperature increased from 23.8 °C to 35.4 °C, determine ΔrU for the combustion of phenol.

Accepted Answer

A)  -8.19 × 103 kJ mol-1
B)  -5.81 × 103 kJ mol-1
C)  4.87 × 103 kJ mol-1
D)  -3.05 × 103 kJ mol-1
E)  2.41 × 103 kJ mol-1

Question 2

Choose the thermochemical equation that illustrates ΔfH° for Li2SO4.

Accepted Answer

A)  2Li+(aq) + SO42-(aq) → Li2SO4(aq) 
B)  2Li(s) + 1/8 S8(s, rhombic) + 2O2(g) → Li2SO4(s) 
C)  Li2SO4(aq) → 2Li+(aq) + SO42-(aq) 
D)  8Li2SO4(s) → 16Li(s) + S8(s, rhombic) + 16O2(g) 
E)  16Li(s) + S8(s, rhombic) + 16O2(g) → 8Li2SO4(s)

Question 3

A balloon is inflated from 0.0100 L to 0.500 L against an external pressure of 10.00 bar. How much work is done in joules? 100 J = 1 L bar

Accepted Answer

A)  -49.0J
B)  49.0 J
C)  0.490 J
D)  -0.490 J
E)  -490 J

Question 4

A 100.0 mL sample of 0.300 mol L-1 NaOH is mixed with a 100.0 mL sample of 0.300 mol L-1 HNO3 in a coffee cup calorimeter. If both solutions were initially at 35.00 °C and the temperature of the resulting solution was recorded as 37.00 °C, determine the ΔrH° (in units of kJ mol-1) for the neutralization reaction between aqueous NaOH and HCl. Assume 1) that no heat is lost to the calorimeter or the surroundings, and 2) that the density and the heat capacity of the resulting solution are the same as water.

Accepted Answer

A)  -55.7 kJ mol-1
B)  -169 kJ mol-1
C)  -16.7 kJ mol-1
D)  -27.9 kJ mol-1
E)  -34.4 kJ mol-1

Question 5

Calculate the mass of sodium cyanate (NaOCN, molar mass = 65.0066 g mol-1) required to lower the temperature from 24.1 °C to 23.0 °C in a coffee cup calorimeter containing 98 mL of water. The enthalpy of solution for NaOCN is 19.20 kJ mol-1. The specific heat of water is 4.184 J g-1 °C-1 and assume the density of the solution is 1.00 g mL-1.

Accepted Answer

A)  0.75 g
B)  1.1 g
C)  3.8 g
D)  1.5 g
E)  4.8 g

Question 6

Which of the following processes is endothermic?

Accepted Answer

A)  an atom emits a photon
B)  the condensation of water
C)  an atom absorbs a photon
D)  the electron affinity of a fluorine atom
E)  None of the above processes is endothermic.

Question 7

Calculate the heat transfer, in kJ, when 1.287 kg of chicken breast (specific heat capacity = 1.82 J g-1 °C-1) is removed from a freezer at -17.3 °C and allowed to warm up to 0.00 °C. You need not be concerned about melting of ice or any other phase changes.

Accepted Answer

A)  -0.0405 kJ
B)  0.0405 kJ
C)  -40.5 kJ
D)  40.5 kJ
E)  8.65 kJ

Question 8

Use the information provided to determine ΔrH° for the following reaction: ΔfH° (kJ mol-1) CH4(g) + 3Cl2(g) → CHCl3(l) + 3HCl(g) ΔrH° = ?
CH4(g)  -75
CHCl3(l) -134
HCl(g)  -92

Accepted Answer

A)  -151 kJ mol-1
B)  -335 kJ mol-1
C)  +662 kJ mol-1
D)  +117 kJ mol-1
E)  -217 kJ mol-1

Question 9

A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter?

Accepted Answer

A)  19 J K-1
B)  28 J K-1
C)  99 J K-1
D)  21 J K-1
E)  76 J K-1

Question 10

Which of the following (with specific heat capacity provided) would show the smallest temperature change upon gaining 200.0 J of heat?

Accepted Answer

A)  50.0 g Al, CAl = 0.903 J g-1 °C-1
B)  50.0 g Cu, CCu = 0.385 J g-1 °C-1
C)  25.0 g granite, Cgranite = 0.79 J g-1 °C-1
D)  25.0 g Au, CAu = 0.128 J g-1 °C-1
E)  25.0 g Ag, CAg = 0.235 J g-1 °C-1

Question 11

What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g mL-1 by 10.2 °C? (The specific heat of the solution is 3.733 J g-1 K-1.)

Accepted Answer

A)  -7.43 kJ
B)  -12.51 kJ
C)  8.20 kJ
D)  -11.9 kJ
E)  6.51 kJ

Question 12

Which of the following processes is exothermic?

Accepted Answer

A)  the formation of dew in the morning
B)  the melting of ice
C)  the chemical reaction in a "cold pack" often used to treat injuries
D)  the vaporization of water
E)  None of the above is exothermic.

Question 13

Calculate the enthalpy of solution for the dissolution of lithium iodide, LiI, molar mass = 133.85 g mol-1. When 1.49 g of LiI is dissolved in a coffee cup calorimeter containing 75.0 mL of water the temperature increased from 23.5 °C to 25.7 °C. The specific heat of water is 4.184 J g-1 °C-1, and assume the density of the solution is 1.00 g mL-1.

Accepted Answer

A)  30 kJ mol-1
B)  18 kJ mol-1
C)  -62 kJ mol-1
D)  -39 kJ mol-1
E)  -76 kJ mol-1

Question 14

What volume of benzene (C6H6, d = 0.88 g mL-1, molar mass = 78.11 g mol-1) is required to produce 1.5 × 103 kJ of heat according to the following reaction? 2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(g) ΔrH° = -6278 kJ

Accepted Answer

A)  75 mL
B)  37 mL
C)  21 mL
D)  19 mL
E)  42 mL

Question 15

Calculate the enthalpy of solution for the dissolution of sodium chloride, NaCl, molar mass = 58.443 g mol-1. When 6.93 g of NaCl is dissolved in a coffee cup calorimeter containing 100.0 mL of water the temperature dropped from 23.5 °C to 22.4 °C. The specific heat of water is 4.184 J g-1 °C-1, and assume the density of the solution is 1.00 g mL-1.

Accepted Answer

A)  -2.8 kJ mol-1
B)  3.9 kJ mol-1
C)  -6.4 kJ mol-1
D)  4.1 kJ mol-1
E)  6.3 kJ mol-1

Question 16

Calculate the final temperature of a 63.7 g piece of palladium, originally at 100.0 °C, placed inside a coffee cup calorimeter containing 115.0 mL of water at 21.8 °C. The specific heat capacity of water is 4.184 J g-1 °C-1, the specific heat capacity of palladium is 0.246 J g-1 °C-1, and the density of water is 1.00 g mL-1.

Accepted Answer

A)  19.3 °C
B)  26.0 °C
C)  32.8 °C
D)  24.3 °C
E)  29.6 °C

Exam 6: Thermochemistry

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Which of the following (with specific heat capacity provided) would show the smallest temperature change upon gaining 200.0 J of heat?

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Use the information provided to determine Δ_rH° for the following reaction: Δ_fH° (kJ mol^-1) CH₄(g) + 3Cl₂(g) → CHCl₃(l) + 3HCl(g) Δ_rH°= ? CH₄(g) -75 CHCl₃(l) -134 HCl(g) -92

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Which of the following processes is endothermic?

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A balloon is inflated from 0.0100 L to 0.500 L against an external pressure of 10.00 bar. How much work is done in joules? 100 J = 1 L bar

Correct Answer
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What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g mL^-1 by 10.2 °C? (The specific heat of the solution is 3.733 J g^-1 K^-1.)

Correct Answer
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Correct Answer
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Correct Answer
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Which of the following processes is exothermic?

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A 2.38 g sample of phenol (C₆H₆O, molar mass = 94.11 g mol^-1) was combusted in a bomb calorimeter with a heat capacity of 6.65 kJ °C^-¹. If the temperature increased from 23.8 °C to 35.4 °C, determine Δ_rU for the combustion of phenol.

Correct Answer
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Choose the thermochemical equation that illustrates Δ_fH° for Li₂SO₄.

Correct Answer
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Correct Answer
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What volume of benzene (C₆H₆, d = 0.88 g mL^-1, molar mass = 78.11 g mol^-1) is required to produce 1.5 × 10³ kJ of heat according to the following reaction? 2C₆H₆(l) + 15O₂(g) → 12CO₂(g) + 6H₂O(g) Δ_rH°= -6278 kJ

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Calculate the heat transfer, in kJ, when 1.287 kg of chicken breast (specific heat capacity = 1.82 J g^-1 °C^-1) is removed from a freezer at -17.3 °C and allowed to warm up to 0.00 °C. You need not be concerned about melting of ice or any other phase changes.

Correct Answer
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Exam 6: Thermochemistry

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Which of the following (with specific heat capacity provided) would show the smallest temperature change upon gaining 200.0 J of heat?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Use the information provided to determine ΔrH° for the following reaction: ΔfH° (kJ mol-1) CH4(g) + 3Cl2(g) → CHCl3(l) + 3HCl(g) ΔrH° = ? CH4(g) -75 CHCl3(l) -134 HCl(g) -92

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Which of the following processes is endothermic?

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A balloon is inflated from 0.0100 L to 0.500 L against an external pressure of 10.00 bar. How much work is done in joules? 100 J = 1 L bar

Correct AnswerverifiedShow Answer

What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g mL-1 by 10.2 °C? (The specific heat of the solution is 3.733 J g-1 K-1.)

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Which of the following processes is exothermic?

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A 2.38 g sample of phenol (C6H6O, molar mass = 94.11 g mol-1) was combusted in a bomb calorimeter with a heat capacity of 6.65 kJ °C-1. If the temperature increased from 23.8 °C to 35.4 °C, determine ΔrU for the combustion of phenol.

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Choose the thermochemical equation that illustrates ΔfH° for Li2SO4.

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What volume of benzene (C6H6, d = 0.88 g mL-1, molar mass = 78.11 g mol-1) is required to produce 1.5 × 103 kJ of heat according to the following reaction? 2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(g) ΔrH° = -6278 kJ

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Calculate the heat transfer, in kJ, when 1.287 kg of chicken breast (specific heat capacity = 1.82 J g-1 °C-1) is removed from a freezer at -17.3 °C and allowed to warm up to 0.00 °C. You need not be concerned about melting of ice or any other phase changes.

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Use the information provided to determine Δ_rH° for the following reaction: Δ_fH° (kJ mol^-1) CH₄(g) + 3Cl₂(g) → CHCl₃(l) + 3HCl(g) Δ_rH°= ? CH₄(g) -75 CHCl₃(l) -134 HCl(g) -92

Correct Answer
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Correct Answer
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Correct Answer
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What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g mL^-1 by 10.2 °C? (The specific heat of the solution is 3.733 J g^-1 K^-1.)

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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A 2.38 g sample of phenol (C₆H₆O, molar mass = 94.11 g mol^-1) was combusted in a bomb calorimeter with a heat capacity of 6.65 kJ °C^-¹. If the temperature increased from 23.8 °C to 35.4 °C, determine Δ_rU for the combustion of phenol.

Correct Answer
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Choose the thermochemical equation that illustrates Δ_fH° for Li₂SO₄.

Correct Answer
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Correct Answer
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What volume of benzene (C₆H₆, d = 0.88 g mL^-1, molar mass = 78.11 g mol^-1) is required to produce 1.5 × 10³ kJ of heat according to the following reaction? 2C₆H₆(l) + 15O₂(g) → 12CO₂(g) + 6H₂O(g) Δ_rH°= -6278 kJ

Correct Answer
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Calculate the heat transfer, in kJ, when 1.287 kg of chicken breast (specific heat capacity = 1.82 J g^-1 °C^-1) is removed from a freezer at -17.3 °C and allowed to warm up to 0.00 °C. You need not be concerned about melting of ice or any other phase changes.

Correct Answer
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