Thermodynamics ❮ 131- Which of the following is the minimum energy
required to initiate a reaction?
(A) free energy
(B) lattice energy
(C) kinetic energy
(D) activation energy - What is the minimum energy required to force a
nonspontaneous reaction to occur?
(A) free energy
(B) lattice energy
(C) kinetic energy
(D) activation energy - A student heats a 25-g sample of lead metal to
65 °C. This sample is immediately clamped in
contact with a 47-g sample of magnesium metal.
The original temperature of the magnesium was
25 °C. No heat was lost to the surroundings
during the experiment. The specific heat of lead
metal is 0.127 J/g °C, and the specific heat of
magnesium metal is 1.024 J/g °C. The final tem-
perature of both metals was 27°C. What is one
possible conclusion the student might postulate
from this experiment?
(A) The lead lost more heat than the magnesium
gained.
(B) The lead lost the same amount of heat as the
magnesium gained.
(C) The lead lost less heat than the magnesium
gained.
(D) The student made an error because the final
temperature should be the average (45°C).
4. What is the energy released when gaseous ions
combine to form an ionic solid?
(A) free energy
(B) lattice energy
(C) kinetic energy
(D) activation energy
5. C(s) + O 2 (g) → CO 2 (g) ΔH = –393.5 kJ
H 2 (g) + (1/2) O 2 (g) → H 2 O(l)
ΔH = –285.8 kJ
C 2 H 2 (g) + (5/2) O 2 (g) → 2 CO 2 (g) + H 2 O(l)
ΔH = –1,299.8 kJ
Given this information, find the enthalpy change
for 2 C(s) + H 2 (g) → C 2 H 2 (g).
(A) 454.0 kJ
(B) –227.0 kJ
(C) 0.0 kJ
(D) 227.0 kJ
6. A 10 g sample of solid mercury metal is sealed
inside a well-insulated, rigid container. The tem-
perature inside the container is at the melting
point of mercury metal (–38.8°C). The system is
well insulated, so it is possible to assume the insu-
lation prevents any energy change with the sur-
roundings. Which of the following is true about
the total energy and the entropy of the system after
equilibrium has been established in the system?
(A) The total energy increases. The total entropy
will increase.
(B) The total energy is constant. The total
entropy is constant.
(C) The total energy is constant. The total
entropy will decrease.
(D) The total energy is constant. The total
entropy will increase.
❯ Review Questions
Use these questions to review the content of this chapter and practice for the AP Chemistry
exam. First are 24 multiple-choice questions similar to what you will encounter in Section I
of the AP Chemistry exam. Following those is a long free-response question like the ones
in Section II of the exam. To make these questions an even more authentic practice for the
actual exam, time yourself following the instructions provided.Multiple-Choice Questions
Answer the following questions in 35 minutes. You may not use a calculator. You may use
the periodic table and the equation sheet at the back of this book.