Chem 12 Acid Base Practice Test KEY
1.
What colour would 1.0 M HCl be in an indicator mixture consisting of phenol red and
thymolphthalein?
A
B
C
D
2.
During a titration, what volume of 0.500 M KOH is necessary to completely neutralize
10.0 mL of 2.00 M CH3COOH?
A
B
C
D
3.
neutral red
thymol blue
thymolpthalein
chlorophenol red
Acid is added to a buffer solution. When equilibrium is reestablished the buffering effect
has resulted in [H3O+]
A
B
C
D
5.
10.0 mL
20.0 mL
25.0 mL
40.0 mL
Which indicator has a Ka = 1.0 x 10-6?
A
B
C
D
4.
red
blue
yellow
colourless
increasing slightly
decreasing slightly
increasing considerably
decreasing considerably
A buffer solution will form when 0.10 M NaF is mixed with an equal volume of
A
B
C
D
0.10 M HF
0.10 M HCl
0.10 M NaCl
0.10 M NaOH
6.
Which of the following statements applies to 1.0 M NH3(aq) but not to 1.0 M NaOH(aq)?
A
B
C
D
7.
8.
In which of the following are the reactants favoured?
A
HNO2 + CN- ⇄ NO2- + HCN
B
H2S + HCO3- ⇄ HS- + H2CO3
C
H3PO4 + NH3 ⇄ H2PO4- + NH4+
D
CH3COOH + PO43- ⇄ CH3COO- + HPO42-
What is the pOH of a solution prepared by adding 0.50 moles of NaOH to prepare 0.50 L
of solution?
A
B
C
D
9.
1.4
1.6
6.3
7.1
x
x
x
x
10-14
10-9
10-6
10-1
Consider the following equilibrium: 2H2O(l) + energy ⇄ H3O+(aq) + OH-(aq)
What will cause the pH to increase and the Kw to decrease?
A
B
C
D
11.
0.00
0.30
14.00
13.70
What is the [H3O+] in a solution with a pH = 5.20?
A
B
C
D
10.
partially ionizes
neutralizes an acid
has a pH greater than 7
turns bromocresol green from yellow to blue
adding a strong acid
adding a strong base
increasing the temperature
decreasing the temperature
The complete neutralization of 15.0 mL of KOH requires 0.0250 moles H2SO4. The
[KOH] was
A
B
C
D
1.50 M
1.67 M
3.33 M
6.67 M
12.
What is the [H3O+] at the equivalence point for the titration between HBr and KOH?
A
1.0 x 10-9 M
B
1.0 x 10-7 M
C
1.0 x 10-5 M
D
0.0 M
13.
Which of the following would form a buffer solution when equal moles are mixed
together?
A
B
C
D
14.
Which of the following acids has the weakest conjugate base?
A
B
C
D
15.
0.010 M
0.050 M
0.10 M
0.20 M
The conjugate base of an acid is produced by
A
B
C
D
17.
HIO3
HNO2
H3PO4
CH3COOH
When 10.0 ml of 0.10 M HCl is added to 10.0 mL of water, the concentration of H3O+ in
the final solution is
A
B
C
D
16.
HCl and NaCl
HCN and NaCN
KNO3 and KOH
Na2SO4 and NaOH
adding a proton to the acid
adding an electron to the acid
removing a proton from the acid
removing an electron from the acid
Which of the following represents the predominant reaction between HCO3- and water?
A
2HCO3- ⇄ H2O + 2CO2
B
HCO3- + H2O ⇄ H2CO3
C
HCO3- + H2O ⇄
D
2HCO3- + H2O ⇄ H3O+ + CO32- + OH- + CO2
+ OH-
H3O+ + CO32-
18.
19.
Water acts as an acid when it reacts with
I
II
III
IV
CNNH3
HClO4
CH3COO-
A
B
C
D
I and IV only
II and III only
I, II, and IV
II, III, and IV
In a solution of 0.10 M H2SO4, the ions present in order of decreasing concentration are
A
B
C
D
[H3O+] > [HSO4-] > [SO42-] > [OH-]
[H3O+] > [SO42-] > [HSO4-] > [OH-]
[OH-] > [SO42-] > [HSO4-] > [H3O+]
[SO42-] > [HSO4-] > [OH-] > [H3O+]
20. Which of the following will dissolve in water to produce an acidic solution?
A
B
C
D
21.
22.
CO2
CaO
MgO
Na2O
Which of the following solutions will have a pH = 1.00?
I
II
III
0.10 M HCl
0.10 M HNO2
0.10 M NaOH
A
B
C
D
I only
II only
I and II only
I, II, and III
Ka for the acid H2AsO4- is 5.6 x 10-8. What is the value of the Kb for HAsO42-?
A
B
C
B
5.6
3.2
1.8
2.4
x
x
x
x
10-22
10-14
10-7
10-4
23.
In a titration, which of the following has a pH = 7.00 at the equivalence point?
A
B
C
D
24.
Which of the following salts dissolves to produce a basic solution?
A
B
C
D
25.
NaCl
LiOH
NH4NO3
KCH3COO
Which of the following will form a basic aqueous solution?
A
B
C
D
28.
1.40
1.70
12.30
13.60
Which of the following solutions has a pH less than 7.00?
A
B
C
D
27.
KCl
NH4Br
Fe(NO3)3
LiCH3COO
Calculate the pH in a 0.200 M solution of Sr(OH)2.
A
B
C
D
26.
NH3 and HNO3
KOH and HCl
NaF and HCl
Ca(OH)2 and CH3COOH
HSO3HSO4HPO42HC2O4-
What is the approximate Ka value for the indicator chlorophenol red?
A
B
C
D
1
1
1
1
x
x
x
x
10-14
10-8
10-6
10-3
29.
What is the approximate pH of the solution formed when 0.040 mol NaOH is added to
2.00 L of 0.020 M HCl?
A
B
C
D
30.
31.
In which one of the following equations are the Bronsted acids and bases all correctly
identified?
Acid
+
Base
⇄
Base
A
H2O2
+
SO32-
⇄
HO2- +
HSO3-
B
H2O2
+
SO32-
⇄
HSO3- +
HO2-
C
SO32-
+
H2O2
⇄
HO2- +
HSO3-
D
SO32-
+
H2O2
⇄
HSO3- +
HO2-
Acid
weak acid with a weak base
strong acid with a weak base
weak acid with a strong base
strong acid with a strong base
A buffer solution may contain equal moles of
A
B
C
D
33.
+
Which of the following titrations will always have an equivalence point at a pH > 7.00?
A
B
C
D
32.
0.00
1.40
1.70
7.00
weak acid and strong base
strong acid and strong base
weak acid and its conjugate base
strong acid and its conjugate base
A gas which is produced by burning coal and also contributes to the formation of acid
rain is
A
B
C
D
H2
O3
SO2
C3H8
34.
Which of the following 1.0 M salt solutions is acidic?
A
B
C
D
35.
Which of the following statements applies to 1.0 M NH3(aq) but not to 1.0 M NaOH(aq)?
A
B
C
D
36.
BaS
NH4Cl
Ca(NO3)2
NaCH3COO
partially ionizes
neutralizes and acid
has a pH greater than 7
turns bromcresol green from yellow to blue
When the indicator thymol blue is added to 0.10 M solution of an unknown acid, the
solution is red. The acid could be
A
B
C
D
HF
H2S
HCN
HNO3
Written:
1.
Calculate the pH of the solution prepared by mixing 15.0 mL of 0.50 M HCl with 35.0
mL 0.50 M NaOH.
HCl
+
→
NaOH
[HCl]diluted
c1v1 = c2v2
(0.50M)(15mL)=c2(50mL)
[H+] = 0.15M
NaCl
[NaOH]diluted
c1v1 = c2v2
(0.50M)(35mL)=c2(50mL)
[OH-] = 0.35M
[OH-]excess = [OH-] – [H+] = 0.20M
pOH = -log[OH-]
pOH =
0.70
+
therefore
pH
=
13.30
HOH
2. Calculate the [OH-] in 0.50 M NH3(aq).
NH3
H2 O
⇄
NH4+ + OH-
I
0.50
0
0
C
x
x
x
x
x
E
0.50 - x (-x is not Sig.)
1.0 x 10-14
Ka(NH4+)
Kb(NH3)
=
Kb
1.0 x 10-14
5.6 x 10-10
=
x2
0.50
x
3.
+
=
=
=
1.786 x 10-5
1.786 x 10-5
[OH-] =
3.0 x 10-3 M
A titration was performed by adding 0.175 M H2C2O4 to a 25.00 mL sample of NaOH.
The following data was collected. Calculate the [NaOH].
Final volume of H2C2O4 from burette (mL)
Initial volume of H2C2O4 from burette (mL)
Trial 1
Trial 2
Trial 3
23.00
4.85
18.15
39.05
23.00
16.05
20.95
5.00
15.95
average to 16.00 mL
reject
H2C2O4
+
0.0160 L
0.175 M
[NaOH]
2NaOH → Na2C2O4
+
2H20
0.0250 L
?M
=
0.0160 L H2C2O4 x 0.175 mole x 2 mole NaOH
L
1 mole H2C2O4
0.0250 L
=
0.224 M
4.
A 250.0 mL sample of HCl with a pH of 2.000 is completely neutralized with 0.200 M
NaOH. What volume of NaOH is required to reach the stoichiometric point.
pH = 2.000 [H+] = 0.010 M
HCl
+
→
NaOH
NaCl +
H2 O
0.2500 L x 0.0100 mole x 1moleNaOH x L
= 0.0125 L
L
1 mole HCl
0.200 mole
5.
If the HCl were titrated with 0.200 M NH3(aq) instead of 0.200 M NaOH, how would the
volume of base required to reach the equivalence point compare with the volume calculated in
the last question? Explain your answer.
It would be the same.
HCl forces the reaction to completion so a weak base is as good as a strong base for
neutralizing a strong acid.
6.
a)
Consider the following salt ammonium acetate, NH4CH3COO.
Write the equation for the dissociation of
NH4CH3COO → NH4+
b)
c)
+
CH3COO-
Write the equations for the hydrolysis reactions that occur.
CH3COO-
+
H2 O
⇄
CH3COOH
NH4+ +
H2 O
⇄
NH3
+
+
OH-
H3O+
Explain why a solution of NH4CH3COO has a pH =7.00. Support your answer with a
calculation.
Ka(NH4+)
= 5.6 x 10-10
Kb(CH3COO-)
=
Kw
1.8 x 10-5
=
5.6 x 10-10
7.
Consider the following equilibrium: energy + 2H2O ⇄ H3O+
a) Explain how pure water can have a pH = 7.30.
+ OH-
At a lower temperature the equilibrium shifts left, the [H3O+] decreases and the pH
increases.
b) Calculate the value of the Kw for the sample of water with a pH = 7.30.
pH = 7.30
[H+] = 10-7.3 = 5.02 x 10-8 M
remember the [H+] = [OH-] = 5.02 x 10-8 M
Kw = [H+][OH-] = (5.02 x 10-8 M)2
= 2.5 x 10-15