Chemistry in Solution (CHMS2208)

BSc, Chemistry - CHMS

Semester: Second Semester

Level: 200

Year: 2016

Answers (200 )
CHMS 2208 Test: June 2016
Answer all questions.
1. Consider the equation: IO
3
-
+ I
-
+ H
+
→ I
2
+ H
2
O
Coefficients of species in the balanced equations in order of species occurring are
A) 2, 10, 12, 6, 6 B. 1, 5, 6, 3, 3 C. 2,3,3,1,5 D. 4,3,2,1,5 E. None
2-4. Consider the following half reactions:
Half reaction E
0
volts
Sn
4+
+ 2e→ Sn
2+
+0.150
Ni
2
+ 2e→ Ni -0.250
Co
2+
+ 2e→ Co -0.277
Li
+
+ 2e→ Li -3.040
Ce
4+
+ 2e→ Ce
3+
+1.61
2. Calculate the standard cell potential for the reaction: 2 Fe
3+
+ Sn
2+
→ 2 Fe
2+
+ Sn
4+
(E
0
Sn
4+
/ Sn
2+
= 0.15V, E
0
Fe
3+
/ Fe
2+
= 0.77V )
A. 0.62V B. 0.92V C. 1.39V D. 1.69V E) none
3. What is the potential of a platinum electrode immersed in a solution containing 0.01M Fe
3+
and 0.10M Fe
2+
(E
0
= 0.771 V)
A. 0.129V B. 0.612 C. 0.712 D. 0.653 E. none
4. Which specie is the most powerful oxidizing agent
Li
+
B. Sn
4+
C. Ce
4+
D. Li
+
5. Which specie is the most powerful reducing agent?
A) Ce
3+
B. Ce
4+
C. Li
+
D. Li E. none
Questions 6-8. The solubility product constant of CaF
2
is 7 x 10
9
. What is
7. The molar solubility of CaF
2
in pure H
2
O : A)1.2x 10
-3
mol/L B) 2.4x 10
-3
mol/L C) 1.2x 10
-3
g/L D) 2.4x 10
-
3
g/L E) 2.4 x 10
-3
moles
8. The molar solubility of CaF
2
in 0.01M NaF: A) 4.5x 10
-3
M B) 7 x 10
-5
M C) None D) 4.2x 10
-4
M E) 1.2x
IO
-4
M
9. The molar solubility of CaF
2
in 0.01M Ca(NO
3
)
2
solution: A) 4.5x IO
-3
M B) 1.2x 10
-3
M C) 4.2x 10
-4
M D)
4.2 x IO
-
4 M E) 2.4x 10
-3
g/L
Set up expressions for the Solubility products of the following substances,
9. Hg
2
Cl
2
: A) [Hg
2
2+
][Cl
-
]
2
, B) [Hg
2
2+
]
2
[Cl
-
]
2
, C) [Hg
2
+
][Cl
-
]
2
, D) [Hg
+
]
2
[Cl
-
]
2
, E) None
10. Ba
3
(ASO
4
)
2
: A) 2[Ba
2+
]
3
[ASO
4
]
2
, B) [Ba
4
]
3
[ASO
4
-3
]
2
, C) 2[Ba
2+
]
3
2[ASO
4
-3
]
-2
, D) 2[Ba
4
]
3
3[ASO
4
-3
]
2
, E)
None
11. Calculate the mean of the following results
21.32% Br, 21.38%Br, 21.5%Br, 21.46%Br, 21.29%Br,
A) 21.20% B) 21.39% C) 21.5% D) 21.30% E) 21.45%
12. What is the range of the values in question 1 above,
A) 42. 80, B) 0.22% C) 22% D) 0.43% E) none
13. Calculate the standard deviation of the above values in question 16,
3.5 B) 0.07 C) 0.09 D) 0.22 E) none
14. calculate the variance of the data in question 11
A) 12.25 B) 0.0049 C) 0.0081 D) 0.0484
Question 15-17: Classify the following as oxyacids, lewis acid, brunsted acids, lewis base and brunsted base.
1 2 3 4 5 6
H
2
SO
4
HCL H
3
PO
4
NH
3
BF
3
OH
-
15. Brunsted acids:
1 and 2 B. 1 and 3 C. 1,2,3 D. 2 and 3 E. 2 only
16. Lewis base:
5 and 4 B. 5 only C. 4 only D. 1 only E. 1
17. Oxyacid: A: 3 only B: 1 and 3 C: 1 only D: 1, 2, 3 E: none
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18. Arrange the following terms of increasing strength: 1) HOCL, 2) HCLO
2
3) HCLO
3
4) HCLO
4
4,3,2,1 B. 1,2,3,4 C. 3,4,1,2 D. 1,3,4,2 E. None
19. What is the concentration of all species in a 0. IM solution of Ba(NO3)2? A) 0.1Ba
2+
and 0.2M NO
3
-
B)
0.2MBa
2+
and 0.1M NO
3
-
C) 0.3M NO
3
-
and 0.15M Ba
2+
D) 0.5M Ba
2+
and 0.1M NO
3
-
E) None
20. The value of [H
+
] in a neutral solution at 25
o
C is A) 10
-14
M B) 1 x 10
-14
M C) 1 x 10
-7
M D) 1 x 10
-9
M
E) none
21. What is the pH of a solution of 0.010M Ca(OH)
2
2.00 B) 5.0 C) 3.0 D) 12.30 E) 8.5
22. What is the pH of a 0.20M HCN? ( Ka = 4.9 x 10
-10
)? A) 3.00 B) 3.5 C) 5.00 D6.5 E) none
23. The product of the acid-dissociation constant for an acid and the base-dissociation constant for its conjugate
base is related to the ion product constant for water as: A) K
a
x K
b
= K
w
B) K
a
x K
w
= K
b
C) K
b
x K
w
= K
a
D)
K
w
= K
b
/ K
a
E) K
w
= K
a
/ K
b
24. What is the normality of a solution Of H
2
SO4 made by dissolving 5.00grams of H
2
SO
4
in enough water to
make 200ml of? A) 0.225N B) 0.325N C) 0.510N D) 0.510N E) None
25. Acidity constants are;
a) The equilibrium positions of acids
b) The degree of equilibrium for acids
c) A measure of the tendency for species to donate protons
d) the measure of the dissociation of species
26. The larger the value of K
b
a) The smaller the value of K
a
and the stronger the base
b) The larger the value of K
a
and the weaker the base
c) The smaller the value of k
a
and the weaker the base
d) None
Consider the following redox equations
I
2
+ HNO
3
→ HIO
3
+ NO + H
2
O
Cr
2
O
7
2-
+ Sn
2+
+ H
+
→ Cr
3+
+ Sn
4+
+ H
2
O
MnO
4
-
+ Cl
-
+ H
+
→ Mn
2+
+ Cl
2
+ H
2
O
The stoichiometric coefficients in the balanced equations are:
27. In 1) a) 3, 10, 6, 10, 2 b) 2,6,10,3,10 c) 3,5,6,5,2 d) none
28. In 2) a) 2,6,28,4,6,14 b) 1,3,14,2,3,7 c) 2,4,28,2,4,14 d) None
29. In 3) a) 1,5,8,1,5,4 b) 4,20,32,4,10,16 c) 2,10,16,2,5,8 d) None
30. The ratio in which acetic acid and sodium acetate must be mixed to give a buffer having a pH 4.50 is:
0.018:1 b) 1:0.018 c) 0.56:1 d) 1:0.56
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