Chemistry in Solution (CHMS2208)

BSc, Chemistry - CHMS

Semester: Resit

Level: 200

Year: 2015

Answers (200 )
REPUBLIC OF CAMEROON THE UNIVERSITY OF BAMENDA
Peace-Work-Fatherland
P. O. BOX 39 Bambili
School/Faculty: _SCIENCE__ Department:_CHEMISTRY_Lecturer(s):_Dr. Nebah B.___
Course Code: _CHMS2206_______ Course Title: Chemistry in solution __
Date: _15/09/2015_______Halls: __ A340-________Time: 14:30 (2 hours)__
Instructions:Answer all questions
Answer all questions
1. The PH of a solution that contains 0.818M acetic acid( Ka = 1.77 X
-5
and 0.172M sodium acetate is
A) 4.077 B) 5.434 C) 8.571 D) 8.370 E) 9.922
2. The pH of a solution prepared by dissolving 0.37 mol of formic acid and 0.23 mol of sodimn formate
jn water to yield 1.OO L of solution (Ka formic acid is 1.77 x 10
-4
is A) 2.1 B) 10.45 C) 3.55 D)
2.31 E) 3.95
3. Which of the following could be added to a solution of sodium acetate to prepare a buffer? i) acetic
acid ii) hydrochloric acid iii) ammonium acetate iv) sodium chloride A) i only B) ii only C) i and ii iii
only E) iv or iii
4. The reaction that takes place when a strong acid is added to an acetic acid -acetate buffer is A)
CH
3
COOH+H
+
→CH
4
+ CO
2
B) CH
3
COOH+H
+
→CH
3
COO
-
+ H
2
C)CH
3
COO
-
+H
+
→CH
3
COOH D)
CH
3
COOH+H
+
→CH
4
+ CO
2
E) CH
3
COOH+H
+
→CH
3
COO
-
+ H
2
OE) None of the above
5. Which one of the following is true for any diprotic acid, H
2
X? A) Ka
2
>Ka
1
B) Ka
2
<Ka
1
C)
Ka
2
=1/Ka
1
D) Ka
2
=Ka
1
E) Ka
1
=1/Ka
2
6. pH of water is 7. When a substance, Y, is dissolved in water, the pH becomes 13. The substance, Y, is
a salt of A) Weak acid and a weak base B) Strong acid and a strong base C) Strong acid and a weak
base D) weak acid and a strong base E) None of the above
7. Which of the following solutions has a pH greater than 7.0? A) 0.10M KBr B)0.10M NH4CI C)
0.10M of HC
2
H
3
O
2
D) 0.10M NaF E) 0.10M HI
8. The pH of solution prepared by mixing 45ml of'0.183 M KOH and65 mL of 0.145 M HC1 is A) 1.31
B)2.92 C)0.74 D)1.97 E) 7.145
9. The pH of solution prepared by mixing 50.0 ml of'0.125 M KOH and 50.0 mL of 0.125 M HC1 is
A6.29 B)7.00 C)8.11 D)5.78 E) 0.00
Questions 10-11: In which of the following aqueous solutions would you expect AgCl to have
10. the lowest solubility? A) Pure water B) 0.02M BaCl
2
C) 0.015 NaCl D) 0.020 AgNO
3
E) 0.020 KCl
11. the highest solubility? A) Pure water B) 0.02M BaCl
2
C) 0.015 NaCl D) 0.020 AgNO
3
E) 0.020 KCl
12. Consider the following overall reaction : 2Rh
+
(aq)
+ Pb
(s)
→2Rh
(s)
+ Pb
2+
(aq)
E
0
=+0.73V.
The E
0
of the half-reaction Rh
+
(aq)
+ e
-
↔ Rh is A)-0.86 V B)-0.60 V C) + 0.60V D)+0.86 V E) None of
the above
13. In a redox reaction, CIO
-
was converted to Cl
-
in a basic solution. The balanced half reaction for this
process is A) CIO
-
+H
2
O +2e
-
→Cl
-
+2OH B) CIO
-
+2OH →Cl
-
+ 2e
-
+H
2
O C) CIO
-
+H
2
O →Cl
-
+2e
-
+2OH
-
D) CIO
-
+2OH
-
+2e
-
→Cl
-
+ H
2
O E) CIO
-
+ 3H
2
O →Cl
-
+3e
-
+3OH
-
14.
Consider the following balanced equation in acidic solution 5H
2
O+ 2CoCl
2
+ OCl
-
→
2C
O
(OH)
3
+ 5CI
-
+ 4H
+
. which of the
following describes the amounts and locations of OH
-
and H
2
O if the equation is balanced in basic solution? A) 1 H
2
O on
the left and 4OH
-
on the right B) 5H
2
O on the left and 4OH
-
on the left C) 1H
2
O on the left and 4OH
-
on the left D) 1H
2
O on
the left and 2OH
-
on the right E) None of the above
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15.
A solution is made containing 6.9 gramsof NaHCO
3
per lOOg of H
2
O. What is the weight percentage of the solute in this
solution? A) 6.9% B)
,
7.5% C) 13.8% D) 6.5% E) none
16.
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
17.
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
18. 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
19.
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
20. The base-dissociation constant , K for the fluoride ion, F
-
( K
a
= 6.8 x 10
-4
) is A) 5.0 X 10
-6
B) 6.2 X
10
-11
C) 5.6 X 10
-6
D) 7.6 X 10
-10
E) 1.5 X 10
-11
Questions 21-22: Set up expressions for the Solubility products of thefollowing substances,
21. 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
22. 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
Questions 23-25 : The solubility product constant of MgF
2
is 7 x 10
9
. What is
23.
The molar solubility ofMgF
2
inpure H
2
O : A)1.2x IO
-3
mol/L B)2.4x IO
-3
mol/L C) 1.2x IO
-3
g/L D) 2.4x IO
-3
g/L E) 2.4 x IO
-
3
moles
24.
The molar solubility ofMgF
2
in 0.01M Mg(NO
3
)
2
solution: A) 4.5x IO
-3
M B) 1.2x IO
-3
M C) 4.2x IO
-3
M D) 2.4x IO
-3
g/L E)
None
25.
The molar solubility ofMgF
2
in 0.01M NaF solution: A) 4.5x IO
-3
M B) 7 x IO
-5
M C) None D) 4.2 x IO
-
4 M E) 1.2x IO
-4
M
26.
Calculate the acid-dissociation constant, Ka for ammonium ion, NH
4
+
(k
b
= 6.8 x IO
-5
). A) 5.6 x IO
-10
B) 6.6 x IO
-9
C) 5.6 x
IO
-9
D) 6.6 x IO
-10
E) 4.5 x IO
-11
Question 27-29 : 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
-
27. Brunsted acids:
A. 1 and 2 B. 1 and 3 C. 1,2,3 D. 2 and 3 E. 2 only
28. Lewis base:
A. 5 and 4 B. 5 only C. 4 only D. 1 only E. 1
29. Oxyacid: A: 3 only B: 1 and 3 C: 1 only D: 1, 2, 3 E: none
30. Arrange the following terms of increasing strength: 1) HOCL, 2) HCLO
2
3) HCLO
3
4) HCLO
4
A. 4,3,2,1 B. 1,2,3,4 C. 3,4,1,2 D. 1,3,4,2 E. None
Questions 31-34: 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
31.
Which specie is the most powerful oxidizing agent
A) Li
+
B. Sn
4+
C. Ce
4+
D. Li
+
32.
Which specie is the most powerful reducing agent?
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A) Ce
3+
B. Ce
4+
C. Li
+
D. Li E. none
33.
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
34.
Calculate the standard cell potential for the reaction: 2Fe
3+
+ Sn
2+
→ 2Fe
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
35.
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
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