The Islamic University of Gaza
Chemistry Department
General Chemistry B.(CHEMB 1301)
Time:2 hours
..............................‫ اسم المدرس‬.............................................. ‫الرقم الجامعي‬
R = 8.314 J/mol.K, or
50
......................................‫اسم الطالب‬
= 0.0821 L.atm/mol.K
Choose the correct answer:
1- Balance the following equation in basic solution and determine the coefficient of H2O and its location (right or
left side) in the equation.
Bi(OH)3 + SnO22  SnO32 + Bi
a. 5, right
b. 3, right
c. 2, right
d. 4, left
2- Determine the value of the equilibrium constant (Keq) at 25oC for the reaction:
Cl2(g) + 2Br ─ (aq)  2Cl ─ (aq) + Br2(l)
Given: Eo Br2(l)/Br- = 1.07 V , Eo Cl2(g)/Cl- = 1.36 V
a. 1.5  10 ─ 10
b. 6.5  109
c. 1.3  1041
d. 8.1  104
3- A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl3 electrolyte. Calculate the
number of moles of gold deposited in 3.0 min by a constant current of 10 A.
1F = 96,500 C
a. 6.2  10 ─ 3 mol
b. 9  10 ─ 3 mol
c. 1.8  10 ─ 2 mol
4- Which statement is true for the following cell?
Zn | Zn2+ (1.0 M) || Sn2+ (1.0 M) | Sn
a. Oxidation occurs at the tin electrode.
b. Electrons will flow from the tin electrode to the zinc electrode.
c. The concentration of Zn2+ will increase.
d. The mass of the tin electrode will decrease.
5- Arrange the following compounds in order of increasing standard molar entropy at 25oC:
C3H8(g), C2H4(g), ZnS(s), and H2O(l).
a. ZnS(s) < H2O(l) < C3H8(g) < C2H4(g)
b. ZnS(s) < C3H8(g) < C2H4(g) < H2O(l)
c. C3H8(g) < C2H4(g) < H2O(l) < ZnS(s)
d. ZnS(s) < H2O(l) < C2H4(g) < C3H8(g)
1
d. 160 mol
6- The equilibrium constant for the reaction: AgBr(s)  Ag+(aq) + Br-─(aq) is Ksp = 7.7  10 ─ 13 at 25oC.
Calculate ΔG for the reaction when [Ag+] = 1.0  10-2 M and [Br-─] = 1.0  10 ─ 3 M. Is the reaction
spontaneous or nonspontaneous at these concentrations?
a. ΔG = 69.1 kJ, nonspontaneous
c. ΔG = 97.5 kJ, spontaneous
b. ΔG = ─69.1 kJ, spontaneous
d. ΔG = 40.6 kJ, nonspontaneous
7- The equilibrium constant at 427oC for the reaction
N2(g) + 3H2(g)  2NH3(g)
is Kp = 9.4  10 ─ 5. Calculate the value of ΔGo for the reaction at 427oC.
a. ─33 kJ
b. ─54 kJ
c. 54 kJ
d. 33 kJ
8- Consider the following reaction:
HgO(s)  Hg(l) + 1/2O2(g)
ΔHo = 90.84 kJ
Use the data given below to estimate the temperature at which this reaction will become spontaneous under
standard conditions.
So(Hg) = 76.02 J/K· mol
So(O2) = 205.0 J/K· mol
So(HgO) = 70.29 J/K· mol
a. 840 K
b. 430 K
c. 620 K
d. 775 K
9- Calculate the pH of a buffer solution which contains 0.25 M benzoic acid (C6H5CO2H) and 0.15 M sodium
benzoate (NaC6H5CO2). Given Ka = 6.5  10 ─ 5.
a. 4.83
b. 3.97
10- The Ksp value for PbCl2 is 2.4  10
a. 2.4  10
c. 7.7  10
─4
─3
─4
c. 3.40
d. 4.41
. What is the molar solubility of PbCl2?
b. 6.2  10
d. 3.9  10
mol/L
mol/L
─2
─2
mol/L
mol/L
11- 50.00 mL of 0.10 M HNO2 (nitrous acid) was titrated with 0.10 M KOH solution. After 25.00 mL of KOH
solution was added, the pH in the titration flask will be:
Given Ka = 4.5  10 ─ 4
a. 2.17
b. 3.35
c. 2.41
2
d. 8.9
12- Which one of the following combinations can't be a buffer solution?
a. HCN and KCN
c. HNO3 and NaNO3
b. NH3 and (NH4)2SO4
d. HF and NaF
13- Take a 10.0 mL solution of a strong acid at pH = 2.00 and a 10.0 mL solution of a strong acid at pH = 6.00 and
mix them. The resulting pH will be:
a. 2.0
b. 2.3
c. 4.0
d. 6.0
14- Which one of the following responses is true with regard to a 0.1 M solution of a strong acid HA?
a. [H+] > [A ─ ]
c. [H+] < [A ─ ]
b. the pH = 1.0
d. the pH > 1.0
15- Calculate the pH of a 0.20 M HA solution. (Ka for HA = 7.2  10 ─ 4 )
a. 1.9
b. 1.6
c. 4.1
d. 3.1
16- At 700 K, the reaction:
2SO2(g) + O2(g)  2SO3(g)
has an equilibrium constant Kc = 4.3  106 , and the following concentrations are present:
[SO2] = 0.010 M; [SO3] = 10 M; [O2] = 0.010 M.
Is the mixture at equilibrium, yes or no? If not at equilibrium, in which direction, left to right, or right to left,
will reaction occur to reach equilibrium.
a. yes
c. no, left to right
b. no, right to left
d. There is not enough information to tell.
17- 1.25 moles of NOCl were placed in a 2.50 L reaction chamber at 427oC. After equilibrium was reached, 1.10
moles of NOCl remained. Calculate the equilibrium constant Kc for the reaction:
2NOCl(g)  2NO(g) + Cl2(g)
a. 3.0  10 ─
4
c. 1.4  10 ─
b. 1.8  103
3
d. 5.6  10 ─
4
18- For the following reaction at equilibrium in a reaction vessel, which one of the changes below would cause the
Br2 concentration to decrease?
2NOBr(g)  2NO(g) + Br2(g) ΔHorxn = 30 kJ
a decrease the container volume
c. Increase the temperature.
b. remove some NO
d. add more NOBr
3
19 A certain first-order reaction A  B is 25% complete in 42 min at 25oC. What is the half-life of the reaction?
a. 21 min
b. 42 min
c. 84 min
d. 101 min
20- The reaction: A + 2B  products, was found to follow the rate law: rate = k[A]2[B].
Predict by what factor the rate of reaction will increase when the concentration of A is doubled and the
concentration of B is tripled, and the temperature remains constant.
a. 5
b. 6
c. 12
d. 18
21- The activation energy for the following reaction is 60 kJ/mol.
Sn2+ + 2Co3+  Sn4+ + 2Co2+
By what factor will the rate constant increase when the temperature is raised from 10oC to 28oC?
A. 5.6
b. 2.8
c. 4.6
d. 696
22- Which of the following aqueous solutions has the highest boiling point? Given Kb = 0.52oC/m.
a. 0.2 m KCl .
c. 0.2 m Ca(NO3)2
b. 0.2 m Na2SO4
d. more than one of the above
23- When 24.0 g of an unknown compound are dissolved in 500 g of water, the solution has a freezing point of
─0.47oC. What is the molar mass of the compound according to the data? Kf = 1.86oC/m.
a. 41.9 g/mol
b. 47.5 g/mol
c. 54.9 g/mol
d. 190 g/mol
24- What is the percent CdSO4 by mass in a 1.0 m aqueous solution (molar mass of CdSO4 = 208.46 g/mol)?
a. 0.001 %
b. 0.10 %
c. 17.2 %
25- Arrange the following in order of increasing boiling point: RbCl, CH3Cl, CH3OH, CH4.
a.
b.
c.
d.
CH3OH < CH3Cl < RbCl < CH4
RbCl < CH3Cl < CH3OH < CH4
CH4 < CH3OH < CH3Cl < RbCl
CH4 < CH3Cl < CH3OH < RbCl
 Good Luck 
4
d. 20.8 %