5 Steps to a 5 AP Chemistry 2019

AP Chemistry Practice Exam 2 ❮ 349

Use the information on the containers in the fol-

lowing diagram to answer questions 31–34 con-

cerning the following equilibrium.

2 Cl 2 (g) + 2 H 2 O(g) ^ 4 HCl(g) + O 2 (g)

ΔH = +100 kJ

Not equilibrium

C

Cl 2

H 2 O

A

Cl 2

H 2 OO 2

B

HCl

Equilibrium

D

Cl 2

H 2 O

O 2

HCl

O 2

HCl

31. An equilibrium mixture (container D) is at 75°C.
    Which of the following changes may increase the
    amount of the HCl in the container?
    (A) Increasing the volume of the container
    (B) Decreasing the volume of the container
    (C) Lowering the temperature of the container
    (D) Adding 1 mole of He(g) to the container


32. Containers A, B, and C are not at equilibrium.
    If each container begins with equal amounts of
    the indicated substances present at the same
    temperature, which of the three will reach equi-
    librium first?
    (A) A because producing products from reac-
    tants is faster than the reverse.
    (B) B because producing reactants from prod-
    ucts is faster than the reverse.
    (C) C because there are both reactants and
    products already in the container.
    (D) It is impossible to determine which will
    reach equilibrium first.


33. If the initial partial pressure of Cl 2 in container
    A is 1.0 atm and the initial partial pressure of
    H 2 O is also 1.0 atm, what will be the pressure at
    equilibrium?
    (A) > 2.0 atm
    (B) = 2.0 atm
    (C) < 2.0 atm
    (D) Impossible to determine
    34. If the moles of HCl in container B are equal to
    five times the O 2 present, what can be said about
    the moles of O 2 present at equilibrium?
    (A) It will be zero because it is the limiting reagent
    (B) It will remain the same
    (C) It will be increase
    (D) It is impossible to determine

Use the following information on the bases in the

following diagram to answer questions 35–37.

H

H

H

Ammonia Methylamine

Dimethylamine Hydroxylamine

N

H

H N

H

H

C H

H

H

H

C

H

H

C H

H

N O

H

H

H

N

Ammonia is only present as a reference. Questions

35–37 only refer to the other three bases.

pH of a 1.0 M solution

Ammonia 11.6

Methylamine 12.9

Dimethylamine 12.5

Hydroxylamine 10.0

35. Solutions of methylamine, dimethylamine, and
    hydroxylamine are titrated. The base concentra-
    tions were 0.1000 M, and 0.1000 M hydrochlo-
    ric acid, HCl, was used for the titrations. Which
    of the three bases will yield the highest pH at the
    equivalence point?
    (A) Hydroxylamine
    (B) Methylamine
    (C) Dimethylamine
    (D) The concentrations of all the bases were the
    same; therefore, the pH at the equivalence
    point will be the same.

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