AP Chemistry — Unit 6 Progress Check: MCQ UPDATED Exam Questions and CORRECT Answers
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Course
AP Chemistry
Institution
AP Chemistry
AP Chemistry — Unit 6 Progress Check:
MCQ UPDATED Exam Questions and
CORRECT Answers
1.
The chemical reaction between HCl(aq) and NH3(aq) is represented above. A student
combines equimolar amounts of HCl(aq) and NH₃(aq), both solutions initially at 24°C, in a
coffee-cup calorimeter. ...
AP Chemistry — Unit 6 Progress Check:
MCQ UPDATED Exam Questions and
CORRECT Answers
1.
The chemical reaction between HCl(aq) and NH3(aq) is represented above. A student
combines equimolar amounts of HCl(aq) and NH₃(aq), both solutions initially at 24°C, in a
coffee-cup calorimeter. The student observes that the mixture reaches a temperature of 28°C.
Based on the experimental results, which of the following can be concluded about the
reaction? - CORRECT ANSWER- C. It is an exothermic process, because energy is released
by the reaction and is gained by the reaction mixture.
2.
When pellets of NaOH(s) are added to a flask of water, it is observed that the temperature of
the water increases as the pellets dissolve. Which of the following claims about the observed
dissolution of NaOH(s) in water is most accurate? - CORRECT ANSWER- C. It is an
exothermic process because heat energy is absorbed by the water as the NaOH(s) dissolves in
it.
3.
An advertisement for a commercial hand warmer claims that the hand warmer works because
a chemical reaction in the hand warmer draws out the body's own natural heat, causing a
warming effect. Which of the following states the accuracy of the claim in the advertisement
and best provides a correct scientific justification of the claim? - CORRECT ANSWER- A.
The advertisement's claim is inaccurate because heat flowing from the hands to the warmer
would only happen if the chemical reaction was endothermic, which would cause the hands
to feel colder.
4.
A student carefully drops a 9.0g solid Zn pellet initially at 50.0°C into an insulated cup
containing 30.0g of water at 27.8°C. The student predicts that the temperature of the water
will increase after the pellet is added. Which of the following statements is the best
justification for the student's prediction? - CORRECT ANSWER- B. Collisions between the
water molecules and the surface of the Zn pellet will result in the transfer of energy,
increasing the average kinetic energy of the water molecules.
, 5.
Two aqueous solutions of equal volume and concentration were kept in flasks and held at
different temperatures. The two solutions were combined in a larger flask. Based on this
information, which of the following predictions is correct? - CORRECT ANSWER- B. The
average kinetic energy of the particles in the cooler solution will increase as they collide with
the particles from the warmer solution.
6.
The table provides data for two CH₃OH(l) samples. Based on this information, which of the
following statements describes what happens when these samples are initially mixed, and
why? - CORRECT ANSWER- D. The CH₃OH molecules from sample 1 transfer thermal
energy to the CH₃OH molecules from sample 2 through collisions because the average kinetic
energy of the molecules in sample 1 is greater.
7.
The graph above shows the changes in temperature recorded for the 2.00 L of H₂O
surrounding a constant-volume container in which a 1.00 g sample of benzoic acid was
combusted. Assume that heat was not absorbed by the container or lost to the surroundings,
that the density of H₂O is 1.00g/mL, and that the specific heat capacity of H₂O is about
4.2J/g⋅°C. Based on this information, estimate how much heat was released from the
combustion of the benzoic acid sample. - CORRECT ANSWER- B. 25 kJ
8.
For an experiment, a 20.0 g piece of Al was placed inside an insulated cup filled with 40.0 g
of H₂O. The data are given in the table above. Assuming no heat is absorbed by the container
or the surroundings, which of the following equations provides the correct mathematical
relationship for the transfer of heat q between Al and H₂O? - CORRECT ANSWER- D. -qAl
= qH₂O
9.
A student dissolves 8.00 g of NH₄NO₃(s) in 100. g of H₂O(l) in a coffee-cup calorimeter.
Based on the initial and final temperatures of the mixture in degrees Celsius shown in the
diagram above the laboratory setup, what is the calculated ∆T of the water reported to the
appropriate number of significant figures? - CORRECT ANSWER- C. -5.5°C
10.
Particulate models of the evaporation of liquid water and the condensation of water vapor are
shown above. Based on these models, which of the following accurately compares the energy
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