Leaders: Kyle and Shealyn
Course: Chem 178
Supplemental Instruction
Iowa State University
Instructors: Burnett and Vela
Date: 2-9-14
1) What are the three kinds of interactions involved in solution formation?
a) Solute-Solute
b) Solute-Solvent
c) Solvent-Solvent
d) All of the above
2) Which of the solutes when dissolved will create a solution with the highest vapor pressure?
a) 0.15m propane
b) 0.2m KBr
c) 0.2m methanol
d) 0.1m MgCl2
3) What is the value of Kc for the following reaction if the equilibrium concentrations are [A] =
0.60 M [B] = 0.35 M [C] = 0.55 M?
2 A (aq) + B (aq) ⇌ 2 C (aq)
a) 0.38
b) 0.42
c) 2.40
d) 2.62
4) Calculate Kc for the reaction CH4 (g) + H2O (g) ⇌ CO (g) + 3 H2 (g). Kp = 7.7 x 1024 at 298
K.
a) 1.28 x 1022
b) 1.28 x 1024
c) 7.7 x 1024
d) 4.61 x 1027
5) Does the reaction in problem 4 favor reactants or products?
a) Reactants
b) Products
6) A 0.700 mole sample of N2O4 (g) is allowed to come to equilibrium with NO2 (g) in a 0.750
L flask. At equilibrium, 0.420 mol N2O4 remains. Calculate the equilibrium concentration of
NO2
N2O4 (g) ⇌ 2 NO2 (g)
a) 0.373 M
b) 0.560 M
c) 0.746 M
d) 1.026 M
7) If the system below is at equilibrium how will increasing the volume of the container shift
the reaction?
H2 (g) + 1/8 S8 (s) ⇌ H2S (g)
∆H = −21 kJ/mol
a) Shift to the products
b) Shift to the reactants
c) No shift
8) Two solutions of sugar with concentrations of 0.25 M and 0.60 M are separated by a
semipermeable membrane. The 0.25 M solution is labeled A and the other is labeled B.
During Osmosis:
a) Sugar molecules move from solution A to B.
b) Water molecules move from solution A to B.
c) Water molecules move from solution B to A.
d) Osmosis does not occur.
9) N2O4 and NO2 have the following equilibrium equation:
2 NO2 (g) ⇌ N2O4 (g)
A closed container held at 298K is filled with N2O4 at a partial pressure of 0.50 atm and NO2
at a partial pressure of 0.60 atm. At equilibrium the partial pressure of N2O4 is measured to be
0.54 atm. What is the value of the equilibrium constant?
a) 0.50
b) 1.04
c) 1.72
d) 2.00
10) Find the molarity of a 21.4 m aqueous HF solution. The density is 1.101g/mL and the molar
mass of HF is 20.01 g/mol.
a) 16.6M
b) 19.2M
c) 21.4M
d) 23.6M
11) Find the molality of a 2 liter aqueous solution that is 18.0M H2SO4. The density of the
solution is 3.1 g/mL and the molar mass of H2SO4 is 98.1 g/mol.
a) 2.90 m
b) 5.81 m
c) 6.74 m
d) 13.5 m
12) What is the expression for the equilibrium constant, Kc, for the following reaction:
Cu(s) + 2 Ag+⇌ Cu2+ + 2Ag (s)
2+
a) [Cu ]/[Ag+]2
b) [Ag]2[Cu2+]/[Cu][Ag+]2
c) [Ag+]2/[Cu2+]
d) [Ag]2/[Cu]
13) Which solute would have the highest molarity when dissolved in water?
a) 4M glucose
b) 2M Ba(OH)2
c) 1.5M NaCl
d) 2.5M ethanol
14) Which solute will cause the lowest vapor pressure when dissolved?
a) 0.2m HCl
b) 0.2m sucrose
c) 0.2m Mg(OH)2
d) 0.3m propanol
15) For the reaction shown below, only PCl3 and Cl2 are present in a 2L container. There is 0.20
mol of PCl3 and 0.15 mol of Cl2. The system is allowed to react and reach equilibrium. The
concentration of PCl5 is measured to be 0.021 M. What is the equilibrium constant?
PCl3 (g) + Cl2 (g) ⇌PCl5 (g)
a) 0.03
b) 0.91
c) 2.46
d) 4.92
16) Calculate the new freezing point of water if 31.65g of NaCl is added to 220 mL of water. The
density of water is 1.00 g/mL, the molar mass of NaCl is 58.44 g/mol, and the freezing point
depression constant for water is 1.86.
a) 4.57 C˚
b) -4.57 C˚
c) 9.15 C˚
d) -9.15 C˚
17) Which substance acts as the Bronsted-Lowry acid in the following reaction?
H2S (aq) + CH3NH2 (aq) ⇌ HS- (aq) + CH3NH3+ (aq)
a) H2S
b) CH3NH3+
c) H2O
d) CH3NH2
18) A solution that has a higher concentration than it’s solubility is called:
a) saturated
b) concentrated
c) super-saturated
d) non-ideal
19) Initially 0.035 moles of SO2, 0.5 moles of SO2Cl2, and 0.08 moles of Cl2 are combined in a 5
liter flask. What is the value of Q and which direction will the reaction proceed to establish
equilibrium?
SO2Cl2 (g) ⇄ SO2 (g) + Cl2 (g)
Kc = 0.078
a) Q = 1.12 x 10-3; forward
b) Q = 1.12 x 10-3; backward
c) Q = 5.6 x 10-3; forward
d) Q = 5.6 x 10-3; backward
20) Which direction will the following reaction favor if Ka for HCl is 1.3 x 106 and Ka for H2CO3
is 4.4 x 10 -7?
HCl (aq) + HCO3- (aq) ⇄ Cl- (aq) + H2CO3 (aq)
a) Don’t know
b) Forward direction
c) Reverse direction
d) Not enough information
21) In the following reaction how will increasing the temperature affect Kc?
4HCl (g) + O2 (g) ⇄ H2O (g) + 2Cl2 (g)
ΔH = -114.4 KJ
a) No change
b) Kc goes up
c) Kc goes down
d) Don’t know
22) Determine the pH of a solution if [OH-] = 1.50 x 10-5
a) 2.40
b) 4.82
c) 9.18
d) 12.03
23) What is the pH of a 0.200 M solution of NaOH at 25 degrees Celsius?
a) 0.40
b) 0.70
c) 13.30
d) 13.60
24) What is the pH of a 0.153 M solution of acetic acid at 25 degrees Celsius? Ka = 1.8 x 10-5
a) 2.78
b) 5.56
c) 8.44
d) 13.18
25) Is it possible to have a negative pH? Why or why not?
a) No, because you can’t have negative concentrations
b) No, because you can’t take the logarithm of a negative number
c) Yes, because you can get a negative number when you take a logarithm
d) Yes, because you can have a concentration of over 1M of hydronium ions