Question 1

Use the following data to calculate the standard heat (enthalpy)  of formation, ΔHf°, of manganese(IV)  oxide, MnO2 (s) . 2MnO2(s)  → 2MnO(s)  + O2(g)  ΔH = 264 kJ
MnO2(s)  + Mn(s)  → 2MnO(s)  ΔH = -240 kJ

Accepted Answer

A)   -504 kJ
B)   -372 kJ
C)   -24 kJ
D)   24 kJ
E)   504 kJF) A) and C)
G) A) and D)

Question 2

The combustion of glucose (C6H12O6)  with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

Accepted Answer

A)   223.5 kcal
B)   335.3 kcal
C)   1402 kcal
D)   2012 kcal
E)   5858 kcalF) C) and D)
G) B) and E)

Question 3

For a reaction in a sealed, rigid container, ΔH is always greater than ΔE.

Accepted Answer

A) True 
 B)False

Question 4

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) A) and C)
G) None of the above

Question 5

What is the final temperature when 20.0 g of water at 25°C is mixed with 30.0 g of water at 80°C?

Accepted Answer

A)   35°C
B)   42°C
C)   53°C
D)   58°C
E)   70°CF) B) and C)
G) C) and D)

Question 6

A 275-g sample of nickel at 100.0°C is placed in 100.0 mL of water at 22.0°C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g·K)

Accepted Answer

A)   39.6°C
B)   40.8°C
C)   61.0°C
D)   79.2°C
E)   82.4°CF) C) and E)
G) A) and D)

Question 7

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

Question 8

Nitric acid, which is among the top 15 chemicals produced in the United States, was first prepared over 1200 years ago by heating naturally occurring sodium nitrate (called saltpeter)  with sulfuric acid and collecting the vapors produced. Calculate ΔH°rxn for this reaction. ΔH°f [NaNO3(s) ] = -467.8 kJ/mol; ΔH°f [NaHSO4(s) ] = -1125.5 kJ/mol; ΔH°f [H2SO4(l)  = -814.0 kJ/mol; ΔH°f [HNO3(g) ] = -135.1 kJ/mol
NaNO3(s)  + H2SO4(l)  → NaHSO4(s)  + HNO3(g)

Accepted Answer

A)   -644.2 kJ
B)   -291.4 kJ
C)   -21.2 kJ
D)   21.2 kJ
E)   644.2 kJF) All of the above
G) B) and C)

Question 9

The highly exothermic thermite reaction, in which aluminum reduces iron(III)  oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s)  + Fe2O3(s)  → 2Fe(s)  + Al2O3(s)  ΔH = -850 kJ
What mass of iron is formed when 725 kJ of heat are released?

Accepted Answer

A)   47 g
B)   65 g
C)   95 g
D)   112 g
E)   130 gF) B) and E)
G) A) and E)

Question 10

The standard heat (enthalpy) of formation of graphite is zero.

Accepted Answer

A) True 
 B)False

Question 11

A common laboratory reaction is the neutralization of an acid with a base. When 50.0 mL of 0.500 M HCl at 25.0°C is added to 50.0 mL of 0.500 M NaOH at 25.0°C in a coffee cup calorimeter, the temperature of the mixture rises to 28.2°C. What is the heat of reaction per mole of acid? Assume the mixture has a specific heat capacity of 4.18 J/(g·K)  and that the densities of the reactant solutions are both 1.00 g/mL.

Accepted Answer

A)   670 J
B)   1300 J
C)   27 kJ
D)   54 kJ
E)   > 100 kJF) A) and E)
G) A) and B)

Question 12

The standard state of a substance in aqueous solution is a 1 M solution.

Accepted Answer

A) True 
 B)False

Question 13

A 1.00 g 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·K) , what is the heat capacity of the copper in J/K?

Accepted Answer

A)   2.79 J/(g·K) 
B)   3.33 J/(g·K) 
C)   13.9 J/(g·K) 
D)   209 J/(g·K) 
E)   None of these choices are correct.F) A) and E)
G) C) and D)

Question 14

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

Question 15

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

Accepted Answer

A)   C(g)  + 2H2(g)  + ½O2(g)  → CH3OH(l) 
B)   C(g)  + 4H(g)  + O(g)  → CH3OH(l) 
C)   C(graphite)  + 4H(g)  + O(g)  → CH3OH(l) 
D)   C(diamond)  + 4H(g)  + O(g)  → CH3OH(l) 
E)   C(graphite)  + 2H2(g)  + ½O2(g)  → CH3OH(l) F) B) and E)
G) A) and E)

Question 16

Galena is the ore from which elemental lead is extracted. In the first step of the extraction process, galena is heated in air to form lead(II)  oxide. 2PbS(s)  + 3O2(g)  → 2PbO(s)  + 2SO2(g)  ΔH = -827.4 kJ
What mass of galena is converted to lead oxide if 975 kJ of heat are liberated?

Accepted Answer

A)   203 g
B)   282 g
C)   406 g
D)   478 g
E)   564 gF) B) and E)
G) A) and D)

Question 17

In which of the following processes is ΔH = ΔE ?

Accepted Answer

A)   Two moles of ammonia gas are cooled from 325°C to 300°C at 1.2 atm.
B)   One gram of water is vaporized at 100°C and 1 atm.
C)   Two moles of hydrogen iodide gas react to form hydrogen gas and iodine gas in a 40-L container.
D)   Calcium carbonate is heated to form calcium oxide and carbon dioxide in a container with variable volume.
E)   One mole of solid carbon dioxide sublimes to the gas phase.F) A) and B)
G) A) and C)

Question 18

ΔE values obtained by bomb calorimetry can be converted to give accurate ΔH values.

Accepted Answer

A) True 
 B)False

Question 19

15.0 g of ice cubes at 0.0°C are combined with 150. g of liquid water at 70.0°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) B) and C)
G) All of the above

Question 20

Two solutions (the system) , each of 25.0 mL volume and at 25.0°C, are mixed in a beaker. A reaction occurs between them, and the temperature rises to 35.0°C. After the products have equilibrated with the surroundings, the temperature is again 25.0°C and the total volume is 50.0 mL. No gases are involved in the reaction. Which one of the following relationships concerning the change from initial to final states (both at 25.0°C)  is correct?

Accepted Answer

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

Exam 6: Thermochemistry Energy Flow and Chemical Change

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
verified

The standard heat (enthalpy) of formation of graphite is zero.

Correct Answer
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Correct Answer
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Correct Answer
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In which of the following processes is ΔH = ΔE ?

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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For a reaction in a sealed, rigid container, ΔH is always greater than ΔE.

Correct Answer
verified

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

Correct Answer
verified

A 275-g sample of nickel at 100.0°C is placed in 100.0 mL of water at 22.0°C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g·K)

Correct Answer
verified

The standard state of a substance in aqueous solution is a 1 M solution.

Correct Answer
verified

What is the final temperature when 20.0 g of water at 25°C is mixed with 30.0 g of water at 80°C?

Correct Answer
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Correct Answer
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Correct Answer
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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 Answer
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The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe₂O₃(s) → 2Fe(s) + Al₂O₃(s) ΔH = -850 kJ What mass of iron is formed when 725 kJ of heat are released?

Correct Answer
verified

Galena is the ore from which elemental lead is extracted. In the first step of the extraction process, galena is heated in air to form lead(II) oxide. 2PbS(s) + 3O₂(g) → 2PbO(s) + 2SO₂(g) ΔH = -827.4 kJ What mass of galena is converted to lead oxide if 975 kJ of heat are liberated?

Correct Answer
verified

Use the following data to calculate the standard heat (enthalpy) of formation, ΔH_f°, of manganese(IV) oxide, MnO₂ (s) . 2MnO₂(s) → 2MnO(s) + O₂(g) ΔH = 264 kJ MnO₂(s) + Mn(s) → 2MnO(s) ΔH = -240 kJ

Correct Answer
verified

ΔE values obtained by bomb calorimetry can be converted to give accurate ΔH values.

Correct Answer
verified

The combustion of glucose (C₆H₁₂O₆) with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

Correct Answer
verified

Exam 6: Thermochemistry Energy Flow and Chemical Change

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

The standard heat (enthalpy) of formation of graphite is zero.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

In which of the following processes is ΔH = ΔE ?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

For a reaction in a sealed, rigid container, ΔH is always greater than ΔE.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A 275-g sample of nickel at 100.0°C is placed in 100.0 mL of water at 22.0°C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g·K)

Correct AnswerverifiedShow Answer

The standard state of a substance in aqueous solution is a 1 M solution.

Correct AnswerverifiedShow Answer

What is the final temperature when 20.0 g of water at 25°C is mixed with 30.0 g of water at 80°C?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s) ΔH = -850 kJ What mass of iron is formed when 725 kJ of heat are released?

Correct AnswerverifiedShow Answer

Galena is the ore from which elemental lead is extracted. In the first step of the extraction process, galena is heated in air to form lead(II) oxide. 2PbS(s) + 3O2(g) → 2PbO(s) + 2SO2(g) ΔH = -827.4 kJ What mass of galena is converted to lead oxide if 975 kJ of heat are liberated?

Correct AnswerverifiedShow Answer

Use the following data to calculate the standard heat (enthalpy) of formation, ΔHf°, of manganese(IV) oxide, MnO2 (s) . 2MnO2(s) → 2MnO(s) + O2(g) ΔH = 264 kJ MnO2(s) + Mn(s) → 2MnO(s) ΔH = -240 kJ

Correct AnswerverifiedShow Answer

ΔE values obtained by bomb calorimetry can be converted to give accurate ΔH values.

Correct AnswerverifiedShow Answer

The combustion of glucose (C6H12O6) with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

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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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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Correct Answer
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Correct Answer
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Correct Answer
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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 Answer
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The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together. 2Al(s) + Fe₂O₃(s) → 2Fe(s) + Al₂O₃(s) ΔH = -850 kJ What mass of iron is formed when 725 kJ of heat are released?

Correct Answer
verified

Galena is the ore from which elemental lead is extracted. In the first step of the extraction process, galena is heated in air to form lead(II) oxide. 2PbS(s) + 3O₂(g) → 2PbO(s) + 2SO₂(g) ΔH = -827.4 kJ What mass of galena is converted to lead oxide if 975 kJ of heat are liberated?

Correct Answer
verified

Use the following data to calculate the standard heat (enthalpy) of formation, ΔH_f°, of manganese(IV) oxide, MnO₂ (s) . 2MnO₂(s) → 2MnO(s) + O₂(g) ΔH = 264 kJ MnO₂(s) + Mn(s) → 2MnO(s) ΔH = -240 kJ

Correct Answer
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Correct Answer
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The combustion of glucose (C₆H₁₂O₆) with oxygen gas produces carbon dioxide and water. This process releases 2803 kJ per mole of glucose. When 3.00 mol of oxygen react in this way with glucose, what is the energy release in kcal? (Hint: Write a balanced equation for the combustion process.)

Correct Answer
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