Question 1

Which of these physical changes would require the release of energy?

Accepted Answer

A)   freezing a liquid
B)   boiling a liquid
C)   melting a solid
D)   all of these
E)   none of these

Question 2

Specific heat capacity is

Accepted Answer

A)   the quantity of heat needed to change the temperature of 1.00 g of a substance by 1 K.
B)   the quantity of heat needed to change the temperature of 1.00 g of a substance by 4.184 K.
C)   the capacity of a substance to gain or lose a 1.00 J of energy in the form of heat.
D)   the temperature change undergone when 1.00 g of a substance absorbs 4.184 J.
E)   the maximum amount of energy in the form of heat that 1.00 g of a substance may absorb without decomposing.

Question 3

Combustion of 2.14 g of liquid benzene (C6H6)  causes a temperature rise of 16.2 °C in a constant-pressure calorimeter that has a heat capacity of 5.53 kJ/°C. What is ?H for the following reaction? C6H6(l)  +  152\frac { 15 } { 2 }215​  O2(g)  ? 6 CO2(g)  + 3 H2O(  ℓ\ellℓ  )

Accepted Answer

A)   -89.5 kJ/mol-rxn
B)   41.8 kJ/mol-rxn
C)   -41.8 kJ/mol-rxn
D)   -3.27 × 103 kJ/mol-rxn
E)   89.5 kJ/mol-rxn

Question 4

How much energy is gained by copper when 68.4 g of copper is warmed from 13.4 °C to 78.4 °C? The specific heat capacity of copper is 0.385 J/(g·°C) .

Accepted Answer

A)   3.53 × 102 J
B)   30.18 J
C)   25.02 J
D)   1.71 × 103 J
E)   2.06 × 103 J

Question 5

Many homes are heated using natural gas. The combustion of natural gas converts

Accepted Answer

A)   chemical potential energy to thermal energy.
B)   thermal energy to mechanical energy.
C)   mechanical energy to chemical potential.
D)   electrostatic energy to mechanical energy.
E)   gravitational energy to acoustic energy.

Question 6

Determine the standard enthalpy of formation of Fe2O3(s)  given the thermochemical equations below. 
Fe(s)  + 3 H2O(  ℓ\ellℓ  )  ? Fe(OH) 3(s)  + 3/2 H2(g) 
?rH° = +160.9 kJ/mol-rxn
H2(g)  + 1/2 O2(g)  ? H2O(  ℓ\ellℓ  ) 
?rH° = -285.8 kJ/mol-rxn
Fe2O3(s)  + 3 H2O(  ℓ\ellℓ  )  ? 2 Fe(OH) 3(s) 
?rH° = +288.6 kJ/mol-rxn

Accepted Answer

A)   -252.6 kJ/mol-rxn
B)   +163.7 kJ/mol-rxn
C)   -824.2 kJ/mol-rxn
D)   +33.2 kJ/mol-rxn
E)   + 890.6 kJ/mol-rxn

Question 7

One statement of the first law of thermodynamics is that

Accepted Answer

A)   the amount of work done on a system is dependent of the pathway.
B)   the total work done on a system must equal the heat absorbed by the system.
C)   the total work done on a system is equal in magnitude, but opposite in sign of the heat absorbed by the system.
D)   the total energy change for a system is equal to the sum of the heat transferred to or from the system and the work done by or on the system.
E)   in any chemical process the heat flow must equal the change in enthalpy.

Question 8

It is relatively easy to change the temperature of a substance that

Accepted Answer

A)   is very massive.
B)   is an insulator.
C)   has a high specific heat capacity.
D)   has a low specific heat capacity.
E)   is brittle.

Question 9

A bomb calorimeter has a heat capacity of 2.47 kJ/K. When a 0.103-g sample of a certain hydrocarbon was burned in this calorimeter, the temperature increased by 2.14 K. Calculate the energy of combustion for 1 g of the hydrocarbon.

Accepted Answer

A)   -5.29 J/g
B)    −5.13×105- 5.13 	imes 10 ^ { 5 }−5.13×105  J/g
C)   -0.120 J/g
D)    −2.4×103- 2.4 	imes 10 ^ { 3 }−2.4×103  J/g
E)   -0.540 J/g

Question 10

What is the change in internal energy of the system (ΔU)  if 65 kJ of heat energy is evolved by the system and 62 kJ of work is done on the system for a certain process?

Accepted Answer

A)   -3 kJ
B)   -127 kJ
C)   -65 kJ
D)   3 kJ
E)   127 kJ

Question 11

What is ?rH° for the following phase change? 
LiF(s)  ? LiF(l) 
Substance  ΔH∘f( kJ/mol−rxn) \quad \Delta H ^ { \circ } {}_f ( \mathrm {~kJ} / \mathrm { mol } - \mathrm { rxn } ) ΔH∘f​( kJ/mol−rxn)  
 LiF⁡(s) −616.93\operatorname { LiF } ( s )  \quad - 616.93LiF(s) −616.93 
 LiF⁡(l) −598.65\operatorname { LiF } ( l )  \quad - 598.65LiF(l) −598.65

Accepted Answer

A)   1215.58 kJ/mol-rxn
B)   18.28 kJ/mol-rxn
C)   -1215.58 kJ/mol-rxn
D)   -18.28 kJ/mol-rxn
E)   0 kJ/mol-rxn

Question 12

In thermodynamics, a(n) ________ is defined as the object, or collection of objects, being studied. The surroundings include everything else.

Accepted Answer

The answer of In thermodynamics, a(n) ________ is defined as...

Question 13

Heat capacity is defined as

Accepted Answer

A)   the amount of heat required to raise the temperature of 1 gram of substance by 1 K.
B)   the amount of heat required to raise the temperature of a substance by 1 K.
C)   the amount of heat required to vaporize a solid or liquid.
D)   the maximum amount of heat that a substance may absorb without decomposing.
E)   4.18 cal/g⋅K.

Question 14

Calculate ΔU of a gas for a process in which the gas absorbs 45 J of heat and does 11 J of work by expanding.

Accepted Answer

A)   -34 J
B)   56 J
C)   -56 J
D)   0 J
E)   34 J

Question 15

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H2O(l)  at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H2O(l)  is 4.18 J/(g·°C) .

Accepted Answer

A)   4.18 J/(g·°
C)  
B)   85.6 J/(g·°
C)  
C)   0.204 J/(g·°
C)  
D)   -0.204 J/(g·°
C)  
E)   20.5 J/(g·°
C)

Question 16

_____ is used to measure the energy evolved or absorbed as heat in a chemical or physical process.

Accepted Answer

A)   Calorimetry
B)   Polarimetry
C)   Coulometry
D)   Spectrometry
E)   Colorimetry

Question 17

The following reaction of iron oxide with aluminum is an exothermic reaction. Fe2O3(s)  + 2 Al(s)  → 2 Fe(s)  + Al2O3(s) 
The reaction of 5.00 g of Fe2O3 with excess Al(s)  evolves 26.6 kJ of energy in the form of heat. Calculate the enthalpy change per mole of Fe2O3.

Accepted Answer

A)   -5.32 kJ/mol
B)   -1.33 × 102 kJ/mol
C)   -2.12 × 104 kJ/mol
D)   -2.12 × 102 kJ/mol
E)   -8.50 × 102 kJ/mol

Question 18

Which of the following chemical equations does not correspond to a standard molar enthalpy of formation?

Accepted Answer

A)   Mg(s)  + C(s)  + 3/2 O2(g)  ? MgCO3(s) 
B)   C(s)  + 1/2 O2(g)  ? CO(g) 
C)   N2(g)  + O2(g)  ? 2 NO(g) 
D)   N2(g)  + 2 O2(g)  ? N2O4(g) 
E)   H2(g)  + 1/2 O2(g)  ? H2O(  ℓ\ellℓ  )

Question 19

Which one of the following statements is INCORRECT?

Accepted Answer

A)   Energy is neither created nor destroyed in chemical reactions.
B)   Kinetic energy is the energy that results from an object's position.
C)   Exothermic processes transfer heat from the system into the surroundings.
D)   Increasing the thermal energy of a gas increases the motion of its atoms.
E)   Energy is the capacity to do work.

Question 20

Hydrazine, N2H4, is a liquid used as a rocket fuel. It reacts with oxygen to yield nitrogen gas and water. 
N2H4(  ℓ\ellℓ  )  + O2(g)  ? N2(g)  + 2 H2O(  ℓ\ellℓ  ) 
The reaction of 6.50 g N2H4 evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted.

Accepted Answer

A)   -19.4 kJ/mol
B)   -25.6 kJ/mol
C)   -126 kJ/mol
D)   -622 kJ/mol
E)   -820. kJ/mol

Exam 6: Principles of Chemical Reactivity: Energy and Chemical Reactions

It is relatively easy to change the temperature of a substance that

Correct Answer
verified

The following reaction of iron oxide with aluminum is an exothermic reaction. Fe₂O₃(s) + 2 Al(s) → 2 Fe(s) + Al₂O₃(s) The reaction of 5.00 g of Fe₂O₃ with excess Al(s) evolves 26.6 kJ of energy in the form of heat. Calculate the enthalpy change per mole of Fe₂O₃.

Correct Answer
verified

Hydrazine, N₂H₄, is a liquid used as a rocket fuel. It reacts with oxygen to yield nitrogen gas and water. N₂H₄( $\ell$ ) + O₂(g) ? N₂(g) + 2 H₂O( $\ell$ ) The reaction of 6.50 g N₂H₄ evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted.

Correct Answer
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Many homes are heated using natural gas. The combustion of natural gas converts

Correct Answer
verified

Which of these physical changes would require the release of energy?

Correct Answer
verified

_____ is used to measure the energy evolved or absorbed as heat in a chemical or physical process.

Correct Answer
verified

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H₂O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H₂O(l) is 4.18 J/(g·°C) .

Correct Answer
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Heat capacity is defined as

Correct Answer
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Combustion of 2.14 g of liquid benzene (C₆H₆) causes a temperature rise of 16.2 °C in a constant-pressure calorimeter that has a heat capacity of 5.53 kJ/°C. What is ?H for the following reaction? C₆H₆(l) + $\frac { 15 } { 2 }$ O₂(g) ? 6 CO₂(g) + 3 H₂O( $\ell$ )

Correct Answer
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Specific heat capacity is

Correct Answer
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Correct Answer
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Which one of the following statements is INCORRECT?

Correct Answer
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What is the change in internal energy of the system (ΔU) if 65 kJ of heat energy is evolved by the system and 62 kJ of work is done on the system for a certain process?

Correct Answer
verified

Which of the following chemical equations does not correspond to a standard molar enthalpy of formation?

Correct Answer
verified

In thermodynamics, a(n) ________ is defined as the object, or collection of objects, being studied. The surroundings include everything else.

Correct Answer
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What is ?_rH° for the following phase change? LiF(s) ? LiF(l) Substance $\quad \Delta H ^ { \circ } {}_f ( \mathrm {~kJ} / \mathrm { mol } - \mathrm { rxn } )$ $\operatorname { LiF } ( s ) \quad - 616.93$ $\operatorname { LiF } ( l ) \quad - 598.65$

Correct Answer
verified

A bomb calorimeter has a heat capacity of 2.47 kJ/K. When a 0.103-g sample of a certain hydrocarbon was burned in this calorimeter, the temperature increased by 2.14 K. Calculate the energy of combustion for 1 g of the hydrocarbon.

Correct Answer
verified

How much energy is gained by copper when 68.4 g of copper is warmed from 13.4 °C to 78.4 °C? The specific heat capacity of copper is 0.385 J/(g·°C) .

Correct Answer
verified

One statement of the first law of thermodynamics is that

Correct Answer
verified

Calculate ΔU of a gas for a process in which the gas absorbs 45 J of heat and does 11 J of work by expanding.

Correct Answer
verified

Exam 6: Principles of Chemical Reactivity: Energy and Chemical Reactions

It is relatively easy to change the temperature of a substance that

Correct AnswerverifiedShow Answer

The following reaction of iron oxide with aluminum is an exothermic reaction. Fe2O3(s) + 2 Al(s) → 2 Fe(s) + Al2O3(s) The reaction of 5.00 g of Fe2O3 with excess Al(s) evolves 26.6 kJ of energy in the form of heat. Calculate the enthalpy change per mole of Fe2O3.

Correct AnswerverifiedShow Answer

Hydrazine, N2H4, is a liquid used as a rocket fuel. It reacts with oxygen to yield nitrogen gas and water. N2H4( ℓ\ellℓ ) + O2(g) ? N2(g) + 2 H2O( ℓ\ellℓ ) The reaction of 6.50 g N2H4 evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted.

Correct AnswerverifiedShow Answer

Many homes are heated using natural gas. The combustion of natural gas converts

Correct AnswerverifiedShow Answer

Which of these physical changes would require the release of energy?

Correct AnswerverifiedShow Answer

_____ is used to measure the energy evolved or absorbed as heat in a chemical or physical process.

Correct AnswerverifiedShow Answer

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H2O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H2O(l) is 4.18 J/(g·°C) .

Correct AnswerverifiedShow Answer

Heat capacity is defined as

Correct AnswerverifiedShow Answer

Combustion of 2.14 g of liquid benzene (C6H6) causes a temperature rise of 16.2 °C in a constant-pressure calorimeter that has a heat capacity of 5.53 kJ/°C. What is ?H for the following reaction? C6H6(l) + 152\frac { 15 } { 2 }215​ O2(g) ? 6 CO2(g) + 3 H2O( ℓ\ellℓ )

Correct AnswerverifiedShow Answer

Specific heat capacity is

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which one of the following statements is INCORRECT?

Correct AnswerverifiedShow Answer

What is the change in internal energy of the system (ΔU) if 65 kJ of heat energy is evolved by the system and 62 kJ of work is done on the system for a certain process?

Correct AnswerverifiedShow Answer

Which of the following chemical equations does not correspond to a standard molar enthalpy of formation?

Correct AnswerverifiedShow Answer

In thermodynamics, a(n) ________ is defined as the object, or collection of objects, being studied. The surroundings include everything else.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A bomb calorimeter has a heat capacity of 2.47 kJ/K. When a 0.103-g sample of a certain hydrocarbon was burned in this calorimeter, the temperature increased by 2.14 K. Calculate the energy of combustion for 1 g of the hydrocarbon.

Correct AnswerverifiedShow Answer

How much energy is gained by copper when 68.4 g of copper is warmed from 13.4 °C to 78.4 °C? The specific heat capacity of copper is 0.385 J/(g·°C) .

Correct AnswerverifiedShow Answer

One statement of the first law of thermodynamics is that

Correct AnswerverifiedShow Answer

Calculate ΔU of a gas for a process in which the gas absorbs 45 J of heat and does 11 J of work by expanding.

Correct AnswerverifiedShow Answer

Correct Answer
verified

The following reaction of iron oxide with aluminum is an exothermic reaction. Fe₂O₃(s) + 2 Al(s) → 2 Fe(s) + Al₂O₃(s) The reaction of 5.00 g of Fe₂O₃ with excess Al(s) evolves 26.6 kJ of energy in the form of heat. Calculate the enthalpy change per mole of Fe₂O₃.

Correct Answer
verified

Hydrazine, N₂H₄, is a liquid used as a rocket fuel. It reacts with oxygen to yield nitrogen gas and water. N₂H₄( $\ell$ ) + O₂(g) ? N₂(g) + 2 H₂O( $\ell$ ) The reaction of 6.50 g N₂H₄ evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted.

Correct Answer
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A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H₂O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H₂O(l) is 4.18 J/(g·°C) .

Correct Answer
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Correct Answer
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Combustion of 2.14 g of liquid benzene (C₆H₆) causes a temperature rise of 16.2 °C in a constant-pressure calorimeter that has a heat capacity of 5.53 kJ/°C. What is ?H for the following reaction? C₆H₆(l) + $\frac { 15 } { 2 }$ O₂(g) ? 6 CO₂(g) + 3 H₂O( $\ell$ )

Correct Answer
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