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Chapter 6:
Thermodynamics: The First Law
1. What can a closed system exchange with its surroundings?
a. Nothing; that is why it is defined as closed.
b. Energy.
c. Matter.
d. Matter and energy.
Answer:
B
2. The transfer of energy to a system is defined by what term?
a. Force.
b. Internal energy.
c. Work.
d. Transfer energy.
Answer:
C
3. U = q is an expression of what?
a. Energy being transferred solely by means of heat.
b. Energy being transferred solely by means of work.
c. The equivalence of heat and work.
d. The equivalence of internal energy and work.
Answer:
A
4. The statement, the internal work of an isolated system is constant, is also known as
what?
a. The first law of thermodynamics.
b. The law of conservation of energy.
c. The law of conservation of mass.
d. None of the above.
Answer:
D
5. Upon what does a state function depend?
a. The work done by or on a system.
b. The present state of a system.
c. The heat of a system.
d. The change of energy produced between two phases of a system.
Answer:
B
6. At constant pressure, to what is the change in enthalpy of a system equal?
a. The internal energy of the system.
b. The work done on the system.
c. The heat supplied to the system.
d. The work done by the system.
Answer:
C
7. Heat capacity is determined by what two measurable factors?
a. Work multiplied by heat supplied.
b. Heat supplied multiplied by temperature change.
c. Work divided by heat supplied.
d. Heat supplied divided by temperature change.
Answer:
D
8. Why are the molar heat capacities of gases made of molecules lower than those of
gases made from monatomic materials?
a. They are not; monatomic gases have lower heat capacities.
b. Because monatomic gases are better able to store internal energy.
c. Because molecular gases are better able to store energy.
d. Because monatomic gases impart energy more efficiently than larger, molecular
gases.
Answer:
A
9. What occurs in the process of sublimation?
a. A gas changes phase directly to a solid.
b. A liquid changes phase directly to a gas.
c. A solid changes phase directly to a gas.
d. A solid changes phase directly to a liquid.
Answer:
C
10. In a heating curve, such as the heating curve for water, what does a section of
horizontal line represent?
a. An increase in internal energy.
b. A phase change.
c. A decrease in enthalpy.
d. None of the above.
Answer:
B
11. What must all thermochemical equations display?
a. One mole of the desired product.
b. One mole of the primary reactant.
c. Heat absorbed or given off.
d. The molar heat capacity.
Answer:
C
12. When a reaction generates a gas versus a liquid what is true about the enthalpy of
reaction?
a. The reaction enthalpy is more.
b. The reaction enthalpy is less.
c. There is no difference.
d. No comparison can be made.
Answer:
B
13. Which is the best statement of Hess’s law?
a. Thermochemical equations for the individual steps of a reaction sequence may be
multiplied to find the total energy of the overall reaction.
b. Thermochemical equations for the individual steps of a reaction sequence may be
combined by multiplication or addition to find the total energy of the overall reaction.
c. Thermochemical equations for the individual steps of a reaction sequence may be
summed to find the total energy of the overall reaction.
d. Thermochemical equations for an entire reaction may be summed to find the enthalpy
for individual steps.
Answer:
C
14. What is the standard enthalpy of formation of a substance?
a. The standard enthalpy of formation is the formation of a substance from its elements.
b. The standard enthalpy of formation is the formation of a substance from its elements
in equimolar quantities.
c. The standard enthalpy of formation is the formation of a substance from its elements
in equimolar quantities in their most stable form.
d. The standard enthalpy of formation is the formation of one mole of a substance from
its elements in their most stable form.
Answer:
D
15. Mean bond enthalpy depends on what molecular property?
a. Bond dissociation energy.
b. Molecular size.
c. Bond length.
d. Bond hybridization.
Answer:
A