Question 1

Which one of the following statements about standard states is incorrect?

Accepted Answer

A)  The standard state of a solid compound is the pure solid.
B)  The standard state of a liquid compound is the pure liquid.
C)  The standard state of a gaseous compound is the gas at a pressure of 1 atmosphere.
D)  The standard state of an aqueous solute is a saturated solution in water.
E)  The standard state of an element is the form in which it is stable at 1 atm and a specified temperature, usually 25°C.F) All of the above
G) C) and E)

Question 2

Calculate q when 28.6 g of water is heated from 22.0°C to 78.3°C.

Accepted Answer

A)  0.385 kJ
B)  1.61 kJ
C)  6.74 kJ
D)  9.37 kJ
E)  1.61 × 10 3 kJF) B) and E)
G) A) and E)

Question 3

For which one of the following reactions will ΔH be approximately (or exactly)  equal to ΔE?

Accepted Answer

A)  H 2( g) + Br 2( g) → 2HBr( g) 
B)  H 2O( l) → H 2O( g) 
C)  CaCO 3( s) → CaO( s) + CO 2( g) 
D)  2H( g) + O( g) → H 2O( l) 
E)  CH 4( g) + 2O 2( g) → CO 2( g) + 2H 2O( l) F) C) and D)
G) A) and E)

Question 4

The Starship Enterprise is caught in a time warp and Spock is forced to use the primitive techniques of the 20th century to determine the specific heat capacity of an unknown mineral. The 307-g sample was heated to 98.7°C and placed into a calorimeter containing 72.4 g of water at 23.6°C. The heat capacity of the calorimeter was 15.7 J/K. The final temperature in the calorimeter was 32.4°C. What is the specific heat capacity of the mineral?

Accepted Answer

A)  0.124 J/(g·K) 
B)  0.131 J/(g·K) 
C)  0.138 J/(g·K) 
D)  0.145 J/(g·K) 
E)  None of these choices are correct.F) A) and D)
G) C) and D)

Question 5

The only way in which a system can do work on the surroundings is by expansion against the external pressure.

Accepted Answer

A) True 
 B)False

Question 6

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Accepted Answer

A)  32.7 kJ
B)  46.5 kJ
C)  75.9 kJ
D)  82.8 kJ
E)  89.7 kJF) A) and E)
G) B) and D)

Question 7

In a phase change of water between the liquid and the gas phases, 770.1 kJ of energy was released by the system. What was the product, and how much of it was formed in the phase change? (Data: H2O(l)  → H2O(g)  ΔH = 44.01 kJ/mol.)

Accepted Answer

A)  315 g water vapor was produced.
B)  17.5 g of water vapor was produced.
C)  17.5 mol of water vapor was produced.
D)  17.5 mol of liquid water was produced.
E)  17.5 g of liquid water was produced.F) A) and C)
G) All of the above

Question 8

Which one of the following equations represents the formation reaction of CH3OH(l) ?

Accepted Answer

A)  C( g) + 2H 2( g) + ½O 2( g) → CH 3OH( l) 
B)  C( g) + 4H( g) + O( g) → CH 3OH( l) 
C)  C(graphite) + 4H( g) + O( g) → CH 3OH( l) 
D)  C(diamond) + 4H( g) + O( g) → CH 3OH( l) 
E)  C(graphite) + 2H 2( g) + ½O 2( g) → CH 3OH( l) F) A) and B)
G) A) and C)

Question 9

Calculate the ΔH°rxn for the following reaction. (ΔH°f [SiO2(s) ] = −910.9 kJ/mol; ΔH°f [SiCl4(g) ] = −657.0 kJ/mol; ΔH°f [HCl(g) ] = −92.3 kJ/mol; ΔH°f [H2O(g) ] = −241.8 kJ/mol) 
SiO2(s)  + 4HCl(g)  → SiCl4(g)  + 2H2O(g)

Accepted Answer

A)  −139.5 kJ
B)  −137.4 kJ
C)  −104.4 kJ
D)  104.4 kJ
E)  139.5 kJF) B) and C)
G) C) and E)

Question 10

Ethylene glycol, used as a coolant in automotive engines, has a specific heat capacity of 2.42 J/(g·K) . Calculate q when 3.65 kg of ethylene glycol is cooled from 132°C to 85°C.

Accepted Answer

A)  −1900 kJ
B)  −420 kJ
C)  −99 kJ
D)  −0.42 kJ
E)  −4.2 × 10 −6 kJF) B) and D)
G) A) and B)

Question 11

Stoichiometric amounts of nitrogen gas and hydrogen gas react in a calorimeter to produce 5.00 g of ammonia gas. The calorimeter temperature rises 0.42°C. The calorimeter and water have a combined heat capacity of 32.16 kJ/K. Calculate the heat of formation of ammonia, ΔHf°, in kJ/mol. The formation reaction for ammonia is: 0.5N2(g)  + 1.5H2(g)  → NH3(g) .

Accepted Answer

A)  −46 kJ/mol
B)  −13.5 kJ/mol
C)  −3.97 kJ/mol
D)  3.97 kJ/mol
E)  13.5 kJ/molF) B) and E)
G) B) and D)

Question 12

A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy, ΔE, of the system.

Accepted Answer

A)  −150 J
B)  150 J
C)  −l000 J
D)  1000 J
E)  575 JF) A) and B)
G) A) and C)

Question 13

A system delivers 225 J of heat to the surroundings while delivering 645 J of work. Calculate the change in the internal energy, ΔE, of the system.

Accepted Answer

A)  −420 J
B)  420 J
C)  −870 J
D)  870 J
E)  −225 JF) A) and B)
G) A) and C)

Question 14

Calculate the ΔH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. ΔH°f [CaCO3(s) ] = −1206.9 kJ/mol; ΔH°f [CaO(s) ] = −635.1 kJ/mol;
ΔH°f [CO2(g) ] = −393.5 kJ/mol
CaCO3(s)  → CaO(s)  + CO2(g)

Accepted Answer

A)  −2235.5 kJ
B)  −1448.5 kJ
C)  −178.3 kJ
D)  178.3 kJ
E)  2235.5 kJF) B) and E)
G) None of the above

Question 15

Use Hess's Law to calculate the enthalpy change for the reaction WO3(s)  + 3H2(g)  → W(s)  + 3H2O(g) 
From the following data:
2W(s)  + 3O2(g)  → 2WO3(s)  ΔH = −1685.4 kJ
2H2(g)  + O2(g)  → 2H2O(g)  ΔH = −477.84 kJ

Accepted Answer

A)  125.9 kJ
B)  252.9 kJ
C)  364.9 kJ
D)  1207.6 kJ
E)  None of these choices are correct.F) A) and D)
G) C) and D)

Question 16

The dissolution of barium hydroxide in water is an exothermic process. Which of the following statements is correct?

Accepted Answer

A)  The enthalpy of solid barium hydroxide plus pure water is less than that of the solution, at the same temperature.
B)  The enthalpy of solid barium hydroxide plus pure water is greater than that of the solution, at the same temperature.
C)  The enthalpy of solid barium hydroxide plus pure water is the same as that of the solution, at the same temperature.
D)  The temperature of the solution is lower than of the barium hydroxide and water before mixing.
E)  When barium hydroxide dissolves in water, the system does work on the surroundings.F) B) and D)
G) C) and D)

Question 17

In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

Accepted Answer

A) True 
 B)False

Question 18

Ethanol, C2H5OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°rxnfor the combustion of ethanol. (ΔH°f [C2H5OH(l) ] = −277.7 kJ/mol; ΔH°f [CO2(g) ] = −393.5 kJ/mol; ΔH°f [H2O(g) ] = −241.8 kJ/mol)

Accepted Answer

A)  −1234.7 kJ
B)  −751.1 kJ
C)  −357.6 kJ
D)  357.6 kJ
E)  1234.7 kJF) A) and B)
G) A) and E)

Question 19

In which one of the following reactions would you expect ΔH to be substantially greater than ΔE (i.e., ΔH > ΔE) ?

Accepted Answer

A)  H 2( g) + Br 2( g) → 2HBr( g) 
B)  CO 2( s) → CO 2( g) 
C)  C 2H 2( g) + H 2( g) → C 2H 4( g) 
D)  H 2O( s) → H 2O( l) 
E)  HCl( aq) + NaOH( aq) → NaCl( aq) + H 2O( l) F) B) and D)
G) A) and B)

Question 20

Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?

Accepted Answer

A)  Δ H 
B)  Δ H > 0, process is exothermic
C)  Δ H 
D)  Δ H > 0, process is endothermic
E)  Δ H = 0, since cold packs are sealedF) B) and D)
G) All of the above

Exam 6: Thermochemistry: Energy Flow and Chemical Change

In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

Correct Answer
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Correct Answer
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Which one of the following statements about standard states is incorrect?

Correct Answer
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A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Correct Answer
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Correct Answer
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Calculate the ΔH°_rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. ΔH°_f [CaCO₃(s) ] = −1206.9 kJ/mol; ΔH°_f [CaO(s) ] = −635.1 kJ/mol; ΔH°_f [CO₂(g) ] = −393.5 kJ/mol CaCO₃(s) → CaO(s) + CO₂(g)

Correct Answer
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A system delivers 225 J of heat to the surroundings while delivering 645 J of work. Calculate the change in the internal energy, ΔE, of the system.

Correct Answer
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For which one of the following reactions will ΔH be approximately (or exactly) equal to ΔE?

Correct Answer
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Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?

Correct Answer
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A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy, ΔE, of the system.

Correct Answer
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In which one of the following reactions would you expect ΔH to be substantially greater than ΔE (i.e., ΔH > ΔE) ?

Correct Answer
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Which one of the following equations represents the formation reaction of CH₃OH(l) ?

Correct Answer
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Calculate q when 28.6 g of water is heated from 22.0°C to 78.3°C.

Correct Answer
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Ethylene glycol, used as a coolant in automotive engines, has a specific heat capacity of 2.42 J/(g·K) . Calculate q when 3.65 kg of ethylene glycol is cooled from 132°C to 85°C.

Correct Answer
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Use Hess's Law to calculate the enthalpy change for the reaction WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g) From the following data: 2W(s) + 3O₂(g) → 2WO₃(s) ΔH = −1685.4 kJ 2H₂(g) + O₂(g) → 2H₂O(g) ΔH = −477.84 kJ

Correct Answer
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The only way in which a system can do work on the surroundings is by expansion against the external pressure.

Correct Answer
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The dissolution of barium hydroxide in water is an exothermic process. Which of the following statements is correct?

Correct Answer
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In a phase change of water between the liquid and the gas phases, 770.1 kJ of energy was released by the system. What was the product, and how much of it was formed in the phase change? (Data: H₂O(l) → H₂O(g) ΔH = 44.01 kJ/mol.)

Correct Answer
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Calculate the ΔH°_rxnfor the following reaction. (ΔH°_f [SiO₂(s) ] = −910.9 kJ/mol; ΔH°_f [SiCl₄(g) ] = −657.0 kJ/mol; ΔH°_f [HCl(g) ] = −92.3 kJ/mol; ΔH°_f [H₂O(g) ] = −241.8 kJ/mol) SiO₂(s) + 4HCl(g) → SiCl₄(g) + 2H₂O(g)

Correct Answer
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Ethanol, C₂H₅OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°_rxnfor the combustion of ethanol. (ΔH°_f [C₂H₅OH(l) ] = −277.7 kJ/mol; ΔH°_f [CO₂(g) ] = −393.5 kJ/mol; ΔH°_f [H₂O(g) ] = −241.8 kJ/mol)

Correct Answer
verified

Exam 6: Thermochemistry: Energy Flow and Chemical Change

In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which one of the following statements about standard states is incorrect?

Correct AnswerverifiedShow Answer

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Calculate the ΔH°rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. ΔH°f [CaCO3(s) ] = −1206.9 kJ/mol; ΔH°f [CaO(s) ] = −635.1 kJ/mol; ΔH°f [CO2(g) ] = −393.5 kJ/mol CaCO3(s) → CaO(s) + CO2(g)

Correct AnswerverifiedShow Answer

A system delivers 225 J of heat to the surroundings while delivering 645 J of work. Calculate the change in the internal energy, ΔE, of the system.

Correct AnswerverifiedShow Answer

For which one of the following reactions will ΔH be approximately (or exactly) equal to ΔE?

Correct AnswerverifiedShow Answer

Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?

Correct AnswerverifiedShow Answer

A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy, ΔE, of the system.

Correct AnswerverifiedShow Answer

In which one of the following reactions would you expect ΔH to be substantially greater than ΔE (i.e., ΔH > ΔE) ?

Correct AnswerverifiedShow Answer

Which one of the following equations represents the formation reaction of CH3OH(l) ?

Correct AnswerverifiedShow Answer

Calculate q when 28.6 g of water is heated from 22.0°C to 78.3°C.

Correct AnswerverifiedShow Answer

Ethylene glycol, used as a coolant in automotive engines, has a specific heat capacity of 2.42 J/(g·K) . Calculate q when 3.65 kg of ethylene glycol is cooled from 132°C to 85°C.

Correct AnswerverifiedShow Answer

Use Hess's Law to calculate the enthalpy change for the reaction WO3(s) + 3H2(g) → W(s) + 3H2O(g) From the following data: 2W(s) + 3O2(g) → 2WO3(s) ΔH = −1685.4 kJ 2H2(g) + O2(g) → 2H2O(g) ΔH = −477.84 kJ

Correct AnswerverifiedShow Answer

The only way in which a system can do work on the surroundings is by expansion against the external pressure.

Correct AnswerverifiedShow Answer

The dissolution of barium hydroxide in water is an exothermic process. Which of the following statements is correct?

Correct AnswerverifiedShow Answer

In a phase change of water between the liquid and the gas phases, 770.1 kJ of energy was released by the system. What was the product, and how much of it was formed in the phase change? (Data: H2O(l) → H2O(g) ΔH = 44.01 kJ/mol.)

Correct AnswerverifiedShow Answer

Calculate the ΔH°rxn for the following reaction. (ΔH°f [SiO2(s) ] = −910.9 kJ/mol; ΔH°f [SiCl4(g) ] = −657.0 kJ/mol; ΔH°f [HCl(g) ] = −92.3 kJ/mol; ΔH°f [H2O(g) ] = −241.8 kJ/mol) SiO2(s) + 4HCl(g) → SiCl4(g) + 2H2O(g)

Correct AnswerverifiedShow Answer

Ethanol, C2H5OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°rxnfor the combustion of ethanol. (ΔH°f [C2H5OH(l) ] = −277.7 kJ/mol; ΔH°f [CO2(g) ] = −393.5 kJ/mol; ΔH°f [H2O(g) ] = −241.8 kJ/mol)

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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Correct Answer
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Calculate the ΔH°_rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. ΔH°_f [CaCO₃(s) ] = −1206.9 kJ/mol; ΔH°_f [CaO(s) ] = −635.1 kJ/mol; ΔH°_f [CO₂(g) ] = −393.5 kJ/mol CaCO₃(s) → CaO(s) + CO₂(g)

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Which one of the following equations represents the formation reaction of CH₃OH(l) ?

Correct Answer
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Correct Answer
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Correct Answer
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Use Hess's Law to calculate the enthalpy change for the reaction WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g) From the following data: 2W(s) + 3O₂(g) → 2WO₃(s) ΔH = −1685.4 kJ 2H₂(g) + O₂(g) → 2H₂O(g) ΔH = −477.84 kJ

Correct Answer
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Correct Answer
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Correct Answer
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In a phase change of water between the liquid and the gas phases, 770.1 kJ of energy was released by the system. What was the product, and how much of it was formed in the phase change? (Data: H₂O(l) → H₂O(g) ΔH = 44.01 kJ/mol.)

Correct Answer
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Calculate the ΔH°_rxnfor the following reaction. (ΔH°_f [SiO₂(s) ] = −910.9 kJ/mol; ΔH°_f [SiCl₄(g) ] = −657.0 kJ/mol; ΔH°_f [HCl(g) ] = −92.3 kJ/mol; ΔH°_f [H₂O(g) ] = −241.8 kJ/mol) SiO₂(s) + 4HCl(g) → SiCl₄(g) + 2H₂O(g)

Correct Answer
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Ethanol, C₂H₅OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°_rxnfor the combustion of ethanol. (ΔH°_f [C₂H₅OH(l) ] = −277.7 kJ/mol; ΔH°_f [CO₂(g) ] = −393.5 kJ/mol; ΔH°_f [H₂O(g) ] = −241.8 kJ/mol)

Correct Answer
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