Chemistry 162. Test Two. March 21, 2014. Name ________________________________________________
R = 8.314 J/mol K = 0.08206 L atm / mol K
ln (k2/k1) = -(Eact/R)(1/T2 – 1/T1)
ln[A]t – ln[A]o = kt
[A]t – [A]o = kt 1 / [A]o– 1 / [A]t = kt
Part One. Twenty-five points (each question is two points)
_____ 1) Which of the following values of k will fit the expression, rate = k[A]2?
a- 0.234 L2/mol2 sec
b- 0.234 1/sec
c- 0.234 L/mol sec
d- 0.234 mol/ L sec
_____ 2) In the reaction, 2 NO2(g)  2 NO(g) + O2(g), the rate of appearance of the NO is
a- equal to the rate of disappearance of the NO2
b- ½ the rate of disappearance of the NO2
c- twice the rate of disappearance of the NO2
d- equal to the rate of disappearance of O2
_____ 3) For the reaction 2 SO2(g) + O2(g) ↔ 2 SO3(g) Ho = -190 kJ, the [SO2] at equilibrium will increase if
a- the temperature of the system is lowered
b- an inert gas is added to the system
c- O2 is added to the system
d- the volume of the system is increased
_____ 4) A first order reaction has k = 2.33 x 10-3 sec-1. What is the half-life of the reaction?
a- 155 sec
b- 297 sec
c- 1200 sec
d- 452 sec
_____ 5) If temperature is increased
1- an exothermic reaction will shift to form more products
2- an exothermic reaction will shift to form more reactants
3- an endothermic reaction will shift to form more products
4- an endothermic reaction will shift to form more reactants
a- 3 and 1 are true
b- 3 and 2 are true
c- 4 and 2 are true
d- 4 and 1 are true
_____ 6) The reaction, SO2(g) + ½ O2(g)  SO3(g), has KP = 6.55 at 627 K. What is the value of Kc at this temperature?
a- 0.0213
b- 3.55
c- 47.0
d- 23.5
_____ 7) The decomposition of NO2 has a rate constant of 0.498 M/sec at 319 oC and 1.81 M/sec at 354 oC. What is the
energy of activation?
a- 57 kJ
b- 86 kJ
c- 156 kJ
d- 114 kJ
_____ 8) A reaction has K = [CO2]/[CO]. The reaction is
a- MgO(s) + CO(g)  Mg(s) + CO2(g)
b- CO(g) + ½ O2 (g)  CO2(g)
c- CO2 (g) + MnO(s)  CO(g) + MnO2(s)
d- H2O(g) + CO (g)  H2(g) + CO2(g)
_____ 9) A decomposition reaction has a half-life that is independent of the initial concentration of the reactant.
a- The reaction is zero order
b- The reaction is first order
c- The reaction is second order
d- The order is not determinable
_____ 10) A graph shows a straight line when 1/[A]t is graphed vs time.
a- The reaction is zero order
b- The reaction is first order
c- The reaction is second order
d- The order is not determinable
_____ 11) In order for a reaction to occur, all of the following must occur except
a- proper orientation of collisions
b- sufficient energy for the reaction to occur
c- multiple steps including a slow step
d- breaking and making of bonds
Part Two.
1) (15 points) Definitions.
Catalyst
Le Chatelier’s principle
Activation energy
Transition state
Molecularity
2) (15 points) In a kinetic study of the reaction
2 NO(g) + O2(g)  2 NO2(g)
Experiment One
Experiment Two
Experiment Three
Initial [NO]
0.0125 M
0.0250 M
0.0125 M
Determine the rate law and the rate constant.
Initial [O2]
0.0253 M
0.0253 M
0.0506 M
Initial rate
0.0281 M/sec
0.112 M/sec
0.0397 M/sec
3) (15 points) The following reaction is set with the following concentrations at 365 K. Kc = 2.14.
1- To reach equilibrium, will the reaction have to move to reactants to products or products to reactants?
2- What are the concentrations at equilibrium?
CO2(g)
0.250 M
+
H2 (g)
0.125 M
 CO(g)
0.500 M
+
H2O(g)
0.200 M