Question 1

A system that does no work but that receives heat from the surroundings has

Accepted Answer

A)   q  0.
B)   q > 0, ΔE 
C)   q = ΔE.
D)   q = -ΔE.
E)   w = ΔE.F) All of the above
G) C) and D)

Question 2

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) All of the above
G) A) and B)

Question 3

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) D) and E)
G) B) and E)

Question 4

A system delivers 1275 J of heat while the surroundings perform 855 J of work on it. Calculate ΔE in J.

Accepted Answer

A)   -2130 J
B)   -420 J
C)   420 J
D)   2130 J
E)   -1275 JF) A) and B)
G) A) and C)

Question 5

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 × 103 kJF) D) and E)
G) C) and D)

Question 6

40.0 g of ice cubes at 0.0°C are combined with 150. g of liquid water at 20.0°C in a coffee cup calorimeter. Calculate the final temperature reached, assuming no heat loss or gain from the surroundings. (Data: specific heat capacity of H2O(l) , c = 4.18 J/g·°C; H2O(s)  → H2O(l)  ΔH = 6.02 kJ/mol)

Accepted Answer

A)   0.0
B)   10.6
C)   30.7
D)   43.2
E)   56.4F) A) and D)
G) A) and C)

Question 7

The enthalpy (H) of liquid water is greater than that of the same quantity of ice at the same temperature.

Accepted Answer

A) True 
 B)False

Question 8

A system that undergoes an adiabatic change and has work done on it by the surroundings has

Accepted Answer

A)   w = ΔE.
B)   w = -ΔE.
C)   w > 0, ΔE 
D)   w  0.
E)   w > ΔE.F) None of the above
G) C) and E)

Question 9

For all processes, both q and w will have the same sign.

Accepted Answer

A) True 
 B)False

Question 10

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)   ΔH 
B)   ΔH > 0, process is exothermic
C)   ΔH 
D)   ΔH > 0, process is endothermic
E)   ΔH = 0, since cold packs are sealedF) A) and E)
G) D) and E)

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

The specific heat capacity c of a metal is approximately related to its molar mass  as follows: c ×  = 3R, where R is the universal gas constant, 8.314 J/mol·K. Use this relationship to identify the metal which has a specific heat capacity of 0.900 J/g·K.

Accepted Answer

A)   Li
B)   Sn
C)   Ca
D)   Al
E)   UF) None of the above
G) B) and E)

Question 13

Sand is converted to pure silicon in a three step process. The third step is SiCl4(g)  + 2Mg(s)  → 2MgCl2(s)  + Si(s)  ΔH = -625.6 kJ
What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Accepted Answer

A)   -25.0 kJ
B)   -7820 kJ
C)   -1.56 × 104 kJ
D)   -3.13 × 104 kJ
E)   None of these choices are correct.F) All of the above
G) C) and E)

Question 14

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) A) and C)
G) D) and E)

Question 15

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g·K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0°C, what is its final temperature?

Accepted Answer

A)   -22.7°C
B)   36.7°C
C)   42.7°C
D)   62.7°C
E)   None of these choices are correct.F) None of the above
G) All of the above

Question 16

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 0.800 atm. The value of w, in J, is

Accepted Answer

A)   -4.0 J.
B)   4.0 J.
C)   -405 J.
D)   405 J.
E)   4.05 × 103 J.F) All of the above
G) A) and B)

Question 17

An ideal gas (the system)  is contained in a flexible balloon at a pressure of 1 atm and is initially at a temperature of 20.°C. The surrounding air is at the same pressure, but its temperature is 25°C. When the system has equilibrated with its surroundings, both systems and surroundings are at 25°C and 1 atm. In changing from the initial to the final state, which one of the following relationships regarding the system is correct?

Accepted Answer

A)   ΔE 
B)   ΔE = 0
C)   ΔH = 0
D)   w > 0
E)   q > 0F) A) and C)
G) B) and E)

Question 18

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) C) and E)
G) A) and B)

Question 19

Calcium hydroxide, which reacts with carbon dioxide to form calcium carbonate, was used by the ancient Romans as mortar in stone structures. The reaction for this process is Ca(OH) 2(s)  + CO2(g)  → CaCO3(s)  + H2O(g)  ΔH = -69.1 kJ
What is the enthalpy change if 3.8 mol of calcium carbonate is formed?

Accepted Answer

A)   -18 kJ
B)   -69 kJ
C)   -73 kJ
D)   -260 kJ
E)   None of these choices are correct.F) A) and B)
G) B) and E)

Question 20

A system initially has an internal energy E of 501 J. It undergoes a process during which it releases 111 J of heat energy to the surroundings, and does work of 222 J. What is the final energy of the system, in J?

Accepted Answer

A)   168 J
B)   390 J
C)   612 J
D)   834 J
E)   This cannot be calculated without more information.F) C) and D)
G) A) and E)

Exam 6: Thermochemistry Energy Flow and Chemical Change

The enthalpy (H) of liquid water is greater than that of the same quantity of ice at the same temperature.

Correct Answer
verified

A system that does no work but that receives heat from the surroundings has

Correct Answer
verified

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g·K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0°C, what is its final temperature?

Correct Answer
verified

A system initially has an internal energy E of 501 J. It undergoes a process during which it releases 111 J of heat energy to the surroundings, and does work of 222 J. What is the final energy of the system, in J?

Correct Answer
verified

For all processes, both q and w will have the same sign.

Correct Answer
verified

A system that undergoes an adiabatic change and has work done on it by the surroundings has

Correct Answer
verified

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
verified

A system delivers 1275 J of heat while the surroundings perform 855 J of work on it. Calculate ΔE in J.

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Sand is converted to pure silicon in a three step process. The third step is SiCl₄(g) + 2Mg(s) → 2MgCl₂(s) + Si(s) ΔH = -625.6 kJ What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Correct Answer
verified

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

Correct Answer
verified

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
verified

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

Correct Answer
verified

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
verified

The specific heat capacity c of a metal is approximately related to its molar mass as follows: c × = 3R, where R is the universal gas constant, 8.314 J/mol·K. Use this relationship to identify the metal which has a specific heat capacity of 0.900 J/g·K.

Correct Answer
verified

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 0.800 atm. The value of w, in J, is

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Exam 6: Thermochemistry Energy Flow and Chemical Change

The enthalpy (H) of liquid water is greater than that of the same quantity of ice at the same temperature.

Correct AnswerverifiedShow Answer

A system that does no work but that receives heat from the surroundings has

Correct AnswerverifiedShow Answer

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g·K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0°C, what is its final temperature?

Correct AnswerverifiedShow Answer

A system initially has an internal energy E of 501 J. It undergoes a process during which it releases 111 J of heat energy to the surroundings, and does work of 222 J. What is the final energy of the system, in J?

Correct AnswerverifiedShow Answer

For all processes, both q and w will have the same sign.

Correct AnswerverifiedShow Answer

A system that undergoes an adiabatic change and has work done on it by the surroundings has

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 1275 J of heat while the surroundings perform 855 J of work on it. Calculate ΔE in J.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Sand is converted to pure silicon in a three step process. The third step is SiCl4(g) + 2Mg(s) → 2MgCl2(s) + Si(s) ΔH = -625.6 kJ What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Correct AnswerverifiedShow Answer

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

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

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

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

The specific heat capacity c of a metal is approximately related to its molar mass as follows: c × = 3R, where R is the universal gas constant, 8.314 J/mol·K. Use this relationship to identify the metal which has a specific heat capacity of 0.900 J/g·K.

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 0.800 atm. The value of w, in J, is

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

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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Sand is converted to pure silicon in a three step process. The third step is SiCl₄(g) + 2Mg(s) → 2MgCl₂(s) + Si(s) ΔH = -625.6 kJ What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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