EXAM 1 REVIEW
Supplemental InstructionIowa State University / Leaders: / Lindsey and Elizabeth
Course: / Chem 178
Instructors: / Schewe-Miller and Bonaccorsi
Date: / 2/8/15
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 maqueous 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+(aq) ⇌ Cu2+(aq) + 2Ag (s)
a)[Cu2+]/[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)A solution that has a higher concentration than it’s solubility is called:
a)saturated
b)concentrated
c)super-saturated
d)non-ideal
18)Initially0.035 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
19)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
20)Which of the following is not affected when a catalyst influences a gaseous chemical reaction?
a)forward and reverse reaction rates
b)initial reaction rate
c)value of activation energy
d)reaction mechanism pathway
e)value of equilibrium constant
21)Identify the nonelectrolyte.
a)NaCl
b)K3PO4
c)CH3OH
d)HCl
22)Given: 2NOCl (g) ⇄ 2NO (g) + Cl2 (g) ΔH = 75 kJ
What change occurs in a system at equilibrium
- If the temperature is decreased?
- If the partial pressure of chlorine gas is increased?
- If the total volume is increased?
23)A solution contains 10.0g of KOH and 900.0 mL of water at 20 0C. The volume of the solution is 904.7 mL. Calculate the mole fraction of KOH.
24)Using the data in Question 22, calculate molality.
(Side note: also know how to calculate mass percent, ppm, ppb, molarity. Try calculating them yourselves! See pages 526-527 for help.)