Question 1

Which represents an enthalpy change at 25 °C and 1 atm that is equal to ΔHof for H2O(l) ?

Accepted Answer

A)  O2(g) + 2H2(g) → 2H2O(l) 
B)  ½O2(g) + H (g) → H2O(g) 
C)  H2(g) + ½O2(g) + → H2O(l) 
D)  2H2O(l) → O2(g) + 2H2(g) 
E)  H2O(l) → ½O2(g) + H2(g) F) A) and B)
G) A) and C)

Question 2

Which of the following is incorrectly matched?

Accepted Answer

A)  Radiant energy; solar energy able to influence global climate patterns
B)  Thermal energy; related to temperature irrespective of the volume
C)  Energy; capacity to do work
D)  Chemical energy; potential energyE) B) and D)
F) C) and D)

Question 3

A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.80 atm.What is W? (1 L·atm = 101.3 J)

Accepted Answer

A)  -4.0 J
B)  +4.0 J
C)  -4.1 ×102 J
D)  +4.1 ×102 J
E)  +81 JF) A) and B)
G) All of the above

Question 4

Ethanol,C2H5OH,is promoted as a clean fuel and is used as an additive in many gasoline mixtures.Calculate the ΔH°rxn for the combustion of ethanol. Substance ΔH°f(kJ/mol) 
C2H5OH(l) -277.0
CO2(g) -393.5
H2O(g) -241.8

Accepted Answer

A)  -1235.4 kJ
B)  -751.8 kJ
C)  -358.3 kJ
D)  358.3 kJ
E)  1235.4 kJF) A) and E)
G) None of the above

Question 5

The heat of solution of ammonium nitrate is 26.2 kJ/mol.If a 5.368 g sample of NH4NO3 is added to 40.0 mL of water in a calorimeter at 23.5°C,what is the final temperature of the solution? The specific heat of water is 4.18 J/g·°C and the heat capacity of the calorimeter is 0.650 kJ/°C.

Accepted Answer

A)  14.3°C
B)  20.8°C
C)  -7.7°C
D)  25.6°C
E)  21.4°CF) A) and D)
G) B) and D)

Question 6

A system that does no work but which transfers heat to the surroundings has

Accepted Answer

A)  q  0.
B)  q 
C)  q > 0,ΔU > 0.
D)  q > 0,ΔU 
E)  q < 0,ΔU = 0.F) A) and B)
G) D) and E)

Question 7

What is the standard enthalpy of formation of liquid methanol,CH3OH(l) ? C(graphite) + O2(g) → CO2(g) 
ΔH°rxn = -393.5 kJ/mol
H2(g) + ½O2→ H2O(l) 
ΔH°rxn = -285.8 kJ/mol
CH3OH(l) + 3/2O2(g) → CO2(g) + 2H2O(l) 
ΔH°rxn = -726.4 kJ/mol

Accepted Answer

A)  -1691.5 kJ/mol
B)  -238.7 kJ/mol
C)  1691.5 kJ/mol
D)  47.1 kJ/mol
E)  -47.1 kJ/molF) A) and B)
G) B) and E)

Question 8

Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l) .What is ΔH° for the combustion of 1 mol of B5H9(s) ? Substance ΔH°f (kJ/mol) 
B2O3(s)  -1273.5
B5H9(s)  +73.2
H2O(l)  -285.8

Accepted Answer

A)  -1486.1 kJ
B)  -1632.5 kJ
C)  -4396.7 kJ
D)  -4652.85 kJ
E)  -9086.1 kJF) B) and D)
G) B) and C)

Question 9

How much heat is released if 35.0 g of ethanol (C2H5OH) burns in excess oxygen? C2H5OH(l) + 3O2(g) → 2 CO2(g) + 3 H2O(l) ΔH°rxn = -1367 kJ/mol

Accepted Answer

A)  1797 kJ
B)  1367 kJ
C)  9.61 × 10-4 kJ
D)  4.78 × 104 kJ
E)  1040 kJF) A) and B)
G) B) and E)

Question 10

Natural gas,or methane,is an important fuel.Combustion of one mole of methane releases 802.3 kJ of energy.How much energy does that represent in kcal? (1 cal = 4.184 J)

Accepted Answer

A)  1.92 × 10-1 kcal
B)  1.92 × 102 kcal
C)  3.36 × 103 kcal
D)  1.92 × 105 kcal
E)  3.36 × 106 kcalF) A) and E)
G) None of the above

Question 11

Using Hess' law,what is ΔH°rxn at 25°C for the following reaction? ClF(g) + F2(g) → ClF3(g) 2ClF(g) + O2(g) → Cl2O(g) + OF2(g) ΔH°rxn = +167.4kJ/mol
2ClF3(g) + 2O2(g) → Cl2O(g) +3OF2(g) ΔH°rxn = +341.4kJ/mol
2F2(g) + O2(g) → 2OF2(g) ΔH°rxn = -43.4 kJ/mol

Accepted Answer

A)  -217.5 kJ/mol
B)  -130.2 kJ/mol
C)  217.5 kJ/mol
D)  -108.7 kJ/mol
E)  465.4 kJ/molF) A) and B)
G) A) and C)

Question 12

ΔH does not depend on the path of a reaction,but ΔU does.

Accepted Answer

A) True 
 B)False

Question 13

A piece of copper metal is initially at 100.0°C.It is dropped into a coffee cup calorimeter containing 50.0 g of water at a temperature of 20.0°C.After stirring,the final temperature of both copper and water is 25.0°C.Assuming no heat losses,and that the specific heat (capacity) of water is 4.18 J/g·°C,what is the heat capacity of the copper in J/°C?

Accepted Answer

A)  2.79 J/°C
B)  3.33 J/°C
C)  13.9 J/°C
D)  209 J/°C
E)  None of these choices is correct.F) All of the above
G) A) and C)

Question 14

Suppose a 0.500-g sample of an organic compound is analyzed via bomb calorimetry.The temperature of the calorimeter is measured over time.At t = 5 min,the combustion reaction is initiated.Below is a plot of the data that are obtained.  Suppose the experiment is repeated under identical conditions,but with a 1.000-g sample of the organic compound.What might a plot of the resulting data look like?

Accepted Answer

A)   
B)   
C)   
D)   
E)   F) D) and E)
G) C) and D)

Question 15

A system which does work on the surroundings with no heat change has

Accepted Answer

A) w B) W > 0,ΔU > 0. C) W > 0,ΔU D) W 0. E) W < 0,ΔU < 0.F) A) and B) G) A) and E)

Question 16

The enthalpy of vaporization of a compound is always positive.

Accepted Answer

A) True 
 B)False

Question 17

When Karl Kaveman adds chilled grog to his new granite mug,he removes 10.9 kJ of energy from the mug.If it has a mass of 625 g and was at 25°C,what is its new temperature? Specific heat capacity of granite = 0.79 J/g·°C.

Accepted Answer

A)  3°C
B)  14°C
C)  22°C
D)  47°C
E)  None of these choices is correct.F) B) and C)
G) A) and D)

Question 18

Given that CaO(s) + H2O(l) → Ca(OH) 2(s) ,ΔH°rxn = -64.8 kJ/mol,how many grams of CaO must react in order to liberate 525 kJ of heat?

Accepted Answer

A)  6.92 g
B)  56.1 g
C)  454 g
D)  606 g
E)  3.40 × 104 gF) A) and B)
G) A) and C)

Question 19

A 1.00-g sample of octane (C8H18) is burned in a bomb calorimeter that has a heat capacity of 5.80 kJ/°C.The temperature of the calorimeter rises from 25.00°C to 33.20°C.What is ΔU per mole for the combustion of octane?

Accepted Answer

A)  -47.6 kJ/mol
B)  -416 kJ/mol
C)  -707 kJ/mol
D)  -5.43 ×103 kJ/mol
E)  -1.86 ×105 kJ/molF) B) and C)
G) B) and D)

Question 20

A Snickers candy bar contains 280 Calories,of which the fat content accounts for 120 Calories.What is the energy of the fat content,in kJ? (1 cal = 4.184 J)

Accepted Answer

A)  5.0 × 10-1 kJ
B)  1.2 kJ
C)  5.0 × 102 kJ
D)  1.2 × 103 kJ
E)  1.6 × 103 kJF) None of the above
G) All of the above

Exam 5: Thermochemistry

A Snickers candy bar contains 280 Calories,of which the fat content accounts for 120 Calories.What is the energy of the fat content,in kJ? (1 cal = 4.184 J)

Correct Answer
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Which of the following is incorrectly matched?

Correct Answer
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Natural gas,or methane,is an important fuel.Combustion of one mole of methane releases 802.3 kJ of energy.How much energy does that represent in kcal? (1 cal = 4.184 J)

Correct Answer
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Correct Answer
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A system which does work on the surroundings with no heat change has

Correct Answer
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A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.80 atm.What is W? (1 L·atm = 101.3 J)

Correct Answer
verified

The heat of solution of ammonium nitrate is 26.2 kJ/mol.If a 5.368 g sample of NH₄NO₃ is added to 40.0 mL of water in a calorimeter at 23.5°C,what is the final temperature of the solution? The specific heat of water is 4.18 J/g·°C and the heat capacity of the calorimeter is 0.650 kJ/°C.

Correct Answer
verified

Which represents an enthalpy change at 25 °C and 1 atm that is equal to ΔH^o_f for H₂O(l) ?

Correct Answer
verified

Correct Answer
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When Karl Kaveman adds chilled grog to his new granite mug,he removes 10.9 kJ of energy from the mug.If it has a mass of 625 g and was at 25°C,what is its new temperature? Specific heat capacity of granite = 0.79 J/g·°C.

Correct Answer
verified

Ethanol,C₂H₅OH,is promoted as a clean fuel and is used as an additive in many gasoline mixtures.Calculate the ΔH°_rxn for the combustion of ethanol. Substance ΔH°_f(kJ/mol) C₂H₅OH(l) -277.0 CO₂(g) -393.5 H₂O(g) -241.8

Correct Answer
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What is the standard enthalpy of formation of liquid methanol,CH₃OH(l) ? C(graphite) + O₂(g) → CO₂(g) ΔH°_rxn = -393.5 kJ/mol H₂(g) + ½O₂→ H₂O(l) ΔH°_rxn = -285.8 kJ/mol CH₃OH(l) + 3/2O₂(g) → CO₂(g) + 2H₂O(l) ΔH°_rxn = -726.4 kJ/mol

Correct Answer
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Given that CaO(s) + H₂O(l) → Ca(OH) ₂(s) ,ΔH°_rxn = -64.8 kJ/mol,how many grams of CaO must react in order to liberate 525 kJ of heat?

Correct Answer
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Using Hess' law,what is ΔH°_rxn at 25°C for the following reaction? ClF(g) + F₂(g) → ClF₃(g) 2ClF(g) + O₂(g) → Cl2O(g) + OF₂(g) ΔH°_rxn = +167.4kJ/mol 2ClF₃(g) + 2O₂(g) → Cl₂O(g) +3OF₂(g) ΔH°_rxn = +341.4kJ/mol 2F₂(g) + O₂(g) → 2OF₂(g) ΔH°_rxn = -43.4 kJ/mol

Correct Answer
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A 1.00-g sample of octane (C₈H₁₈) is burned in a bomb calorimeter that has a heat capacity of 5.80 kJ/°C.The temperature of the calorimeter rises from 25.00°C to 33.20°C.What is ΔU per mole for the combustion of octane?

Correct Answer
verified

A system that does no work but which transfers heat to the surroundings has

Correct Answer
verified

Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l) .What is ΔH° for the combustion of 1 mol of B₅H₉(s) ? Substance ΔH°_f (kJ/mol) B₂O₃(s) -1273.5 B₅H₉(s) +73.2 H₂O(l) -285.8

Correct Answer
verified

The enthalpy of vaporization of a compound is always positive.

Correct Answer
verified

How much heat is released if 35.0 g of ethanol (C₂H₅OH) burns in excess oxygen? C₂H₅OH(l) + 3O₂(g) → 2 CO₂(g) + 3 H₂O(l) ΔH°_rxn = -1367 kJ/mol

Correct Answer
verified

ΔH does not depend on the path of a reaction,but ΔU does.

Correct Answer
verified

Exam 5: Thermochemistry

A Snickers candy bar contains 280 Calories,of which the fat content accounts for 120 Calories.What is the energy of the fat content,in kJ? (1 cal = 4.184 J)

Correct AnswerverifiedShow Answer

Which of the following is incorrectly matched?

Correct AnswerverifiedShow Answer

Natural gas,or methane,is an important fuel.Combustion of one mole of methane releases 802.3 kJ of energy.How much energy does that represent in kcal? (1 cal = 4.184 J)

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A system which does work on the surroundings with no heat change has

Correct AnswerverifiedShow Answer

A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.80 atm.What is W? (1 L·atm = 101.3 J)

Correct AnswerverifiedShow Answer

The heat of solution of ammonium nitrate is 26.2 kJ/mol.If a 5.368 g sample of NH4NO3 is added to 40.0 mL of water in a calorimeter at 23.5°C,what is the final temperature of the solution? The specific heat of water is 4.18 J/g·°C and the heat capacity of the calorimeter is 0.650 kJ/°C.

Correct AnswerverifiedShow Answer

Which represents an enthalpy change at 25 °C and 1 atm that is equal to ΔHof for H2O(l) ?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

When Karl Kaveman adds chilled grog to his new granite mug,he removes 10.9 kJ of energy from the mug.If it has a mass of 625 g and was at 25°C,what is its new temperature? Specific heat capacity of granite = 0.79 J/g·°C.

Correct AnswerverifiedShow Answer

Ethanol,C2H5OH,is promoted as a clean fuel and is used as an additive in many gasoline mixtures.Calculate the ΔH°rxn for the combustion of ethanol. Substance ΔH°f(kJ/mol) C2H5OH(l) -277.0 CO2(g) -393.5 H2O(g) -241.8

Correct AnswerverifiedShow Answer

What is the standard enthalpy of formation of liquid methanol,CH3OH(l) ? C(graphite) + O2(g) → CO2(g) ΔH°rxn = -393.5 kJ/mol H2(g) + ½O2→ H2O(l) ΔH°rxn = -285.8 kJ/mol CH3OH(l) + 3/2O2(g) → CO2(g) + 2H2O(l) ΔH°rxn = -726.4 kJ/mol

Correct AnswerverifiedShow Answer

Given that CaO(s) + H2O(l) → Ca(OH) 2(s) ,ΔH°rxn = -64.8 kJ/mol,how many grams of CaO must react in order to liberate 525 kJ of heat?

Correct AnswerverifiedShow Answer

Using Hess' law,what is ΔH°rxn at 25°C for the following reaction? ClF(g) + F2(g) → ClF3(g) 2ClF(g) + O2(g) → Cl2O(g) + OF2(g) ΔH°rxn = +167.4kJ/mol 2ClF3(g) + 2O2(g) → Cl2O(g) +3OF2(g) ΔH°rxn = +341.4kJ/mol 2F2(g) + O2(g) → 2OF2(g) ΔH°rxn = -43.4 kJ/mol

Correct AnswerverifiedShow Answer

A 1.00-g sample of octane (C8H18) is burned in a bomb calorimeter that has a heat capacity of 5.80 kJ/°C.The temperature of the calorimeter rises from 25.00°C to 33.20°C.What is ΔU per mole for the combustion of octane?

Correct AnswerverifiedShow Answer

A system that does no work but which transfers heat to the surroundings has

Correct AnswerverifiedShow Answer

Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l) .What is ΔH° for the combustion of 1 mol of B5H9(s) ? Substance ΔH°f (kJ/mol) B2O3(s) -1273.5 B5H9(s) +73.2 H2O(l) -285.8

Correct AnswerverifiedShow Answer

The enthalpy of vaporization of a compound is always positive.

Correct AnswerverifiedShow Answer

How much heat is released if 35.0 g of ethanol (C2H5OH) burns in excess oxygen? C2H5OH(l) + 3O2(g) → 2 CO2(g) + 3 H2O(l) ΔH°rxn = -1367 kJ/mol

Correct AnswerverifiedShow Answer

ΔH does not depend on the path of a reaction,but ΔU does.

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
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Correct Answer
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The heat of solution of ammonium nitrate is 26.2 kJ/mol.If a 5.368 g sample of NH₄NO₃ is added to 40.0 mL of water in a calorimeter at 23.5°C,what is the final temperature of the solution? The specific heat of water is 4.18 J/g·°C and the heat capacity of the calorimeter is 0.650 kJ/°C.

Correct Answer
verified

Which represents an enthalpy change at 25 °C and 1 atm that is equal to ΔH^o_f for H₂O(l) ?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Ethanol,C₂H₅OH,is promoted as a clean fuel and is used as an additive in many gasoline mixtures.Calculate the ΔH°_rxn for the combustion of ethanol. Substance ΔH°_f(kJ/mol) C₂H₅OH(l) -277.0 CO₂(g) -393.5 H₂O(g) -241.8

Correct Answer
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What is the standard enthalpy of formation of liquid methanol,CH₃OH(l) ? C(graphite) + O₂(g) → CO₂(g) ΔH°_rxn = -393.5 kJ/mol H₂(g) + ½O₂→ H₂O(l) ΔH°_rxn = -285.8 kJ/mol CH₃OH(l) + 3/2O₂(g) → CO₂(g) + 2H₂O(l) ΔH°_rxn = -726.4 kJ/mol

Correct Answer
verified

Given that CaO(s) + H₂O(l) → Ca(OH) ₂(s) ,ΔH°_rxn = -64.8 kJ/mol,how many grams of CaO must react in order to liberate 525 kJ of heat?

Correct Answer
verified

Using Hess' law,what is ΔH°_rxn at 25°C for the following reaction? ClF(g) + F₂(g) → ClF₃(g) 2ClF(g) + O₂(g) → Cl2O(g) + OF₂(g) ΔH°_rxn = +167.4kJ/mol 2ClF₃(g) + 2O₂(g) → Cl₂O(g) +3OF₂(g) ΔH°_rxn = +341.4kJ/mol 2F₂(g) + O₂(g) → 2OF₂(g) ΔH°_rxn = -43.4 kJ/mol

Correct Answer
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A 1.00-g sample of octane (C₈H₁₈) is burned in a bomb calorimeter that has a heat capacity of 5.80 kJ/°C.The temperature of the calorimeter rises from 25.00°C to 33.20°C.What is ΔU per mole for the combustion of octane?

Correct Answer
verified

Correct Answer
verified

Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l) .What is ΔH° for the combustion of 1 mol of B₅H₉(s) ? Substance ΔH°_f (kJ/mol) B₂O₃(s) -1273.5 B₅H₉(s) +73.2 H₂O(l) -285.8

Correct Answer
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Correct Answer
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How much heat is released if 35.0 g of ethanol (C₂H₅OH) burns in excess oxygen? C₂H₅OH(l) + 3O₂(g) → 2 CO₂(g) + 3 H₂O(l) ΔH°_rxn = -1367 kJ/mol

Correct Answer
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Correct Answer
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