Download AP CHEMISTRY CHAPTER 11 PROBLEM SET #4

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AP CHEMISTRY
CHAPTER 11
PROBLEM SET #4
(Questions 1-2) Select the letter that best completes the statement or answers the
question.
_____ 1.
HCN(aq) + H2O(l) -- H3O+(aq) + CN-(aq)
In the equilibrium represented above, the species that act as bases include
which of the following?
I. CN-
II. H2O
A.
B.
C.
D.
E.
_____ 2.
III.
HCN
II only
III only
I and II
I and III
II and III
For oxyacids that vary only by the number of oxygens (i.e., HAO, HAO2,
HAO3), which of the following occurs as the number of oxygen atoms
increases?
A.
It is impossible to predict the acid strength.
B.
The strength of the acid increases.
C.
The strength of the acid decreases only if A is a nonmetal.
D.
The strength of the acid decreases only if A is a metal.
E.
The strength of the acid decreases whether A is a nonmetal or a
metal.
3.
Arrange the following 0.10 M solutions in order from most acidic to most basic:
Ca(NO3)2
NaNO2
HNO3 NH4NO3
Ca(OH)2
4.
Calculate the concentrations of all species present in a 0.25 M solution of
ethylammonium chloride (C2H5NH3Cl).
5.
6.
Calculate the pH of the following solutions:
a.
0.12 M NaNO2
b.
0.45 M NaOCl
c.
0.40 M NH4ClO4
Consider a solution of an unknown salt having the general formula BHCl, where
B is one of the weak bases in the table in your textbook. A 0.10 M solution of the
unknown salt has a pH of 5.82. What is the actual formula of the salt.
7.
Calculate the pH of a 0.10 M CoCl3 solution. Ka for Co(H2O)63+ is 1.0 X 10-5.
8.
Are solutions of the following salts, acidic, basic or neutral? Support your answer.
a.
KCl
9.
b.
NH4C2H3O2
c.
CH3NH3Cl
Place the species in each of the following groups in order of increasing base
strength. Give your reasoning for each.
a.
BrO-, BrO2-,
b.
ClO2-,
BrO2-,
BrO3-
IO2-
10.
Place the species in each of the following groups in order of increasing acid
strength.
a.
H2O, H2S, H2Se (bond energies: H-O, 467 kJ/mol; H-S, 363 kJ/mol; HSe, 276 kJ/mol)
b.
11.
Will the following oxides give acidic, basic or neutral solutions when dissolved in
water? Write reactions to justify your answers.
a.
Na2O
b.
12.
CH3CO2H, FCH2CO2H, F2CHCO2H, F3CCO2H
P4O10
Identify the Lewis acid and the Lewis base in each of the following reactions:
a.
I2 + I-
b.
Zn(OH)2 + 2OH- -----
-----
I3-
Zn(OH)42-
c.
13.
Fe3+
+ SCN- -
FeSCN2+
Calculate the pH of a 10.0 mL solution of C18H21NO3 containing 5.0 mg of
C18H21NO3 if the pKb is 6.05. (pKb = -log Kb). This is a solution that produces a
base.
ANSWERS:
1.
C
2.
B
3.
HNO3, NH4NO3, Ca(NO3), NaNO2, Ca(OH)2
4.
[H+] and [C2H5NH2] = 2.1 X 10-6 M
[C2H5NH3+] = .25 M (.25 – 2.1X 10-6 = .25 with sig figs)
[OH-] = 4.8 X 10-9 M
5.
a.
8.23
b.
10.56
c.
4.82
6.
CH3NH2- methylamine
7.
3.00
8.
a.
neutral
b.
neutral
c.
acidic
9.
a.
BrO3- < BrO2- < BrOb.
HClO2- < HBrO2 < HIO210.
a.
H2O < H2S < H2Se
b.
CH3CO2H, FCH2CO2H, F2CHCO2H, F3CCO2H
11.
a.
basic
b.
acidic
12.
a.
I2 = acid; I- = basic
b.
Zn(OH)2 = acid; OH- = base
c.
Fe3+ = acid; SCN- = base
13.
9.59