1. KEY
GENERAL CHEMISTRY-II (1412)
S.I. # 12
1. Define chemical kinetics:
Chemical kinetics is the study of time vs. rate of chemical change
2. What three factors affect chemical reactions?
1.___concentration______
2.____temperature_________
3.____catalyst__________
3. Define instantaneous rate:
Instantaneous rate is the slope of a line drawn tangent to the concentration-vs.-
time curve at a specific time.
4. What is Beer’s Law?
Beer’s Law is the absorption of electromagnetic radiation by a substance at a
particular wavelength and is directly proportional to its concentration.
5. What is the 1st order of reaction?
1st order of reaction is where the rate is proportional to the concentration of a
single reactant raised to the 1st power: Over all reaction order of 1. Rate = k[A], graphs
of ln[A] vs. time yields a straight line slope of –k.
6. What is the 2nd order of reaction?
The overall reaction order is 2. Rate = k[A]2
The graph also gives straight line.
7. What is half-life?
t1/2 = time required for the concentration of a reactant to decrease to ½ its initial
value.
8. What is activation energy?
(Ea) = the minimum energy for a reaction to occur or to remove one electron.

2. KEY
9. What is the Arrhenius Equation?
k = Ae-Ea/RT or k = ln A – Ea/RT
the graph gives a slope of –Ea/R
10. What is an intermediate step?
An intermediate step is produced in one elementary step and is consumed later in
another elementary step. It does not appear in the over all equation or reaction.
11. What is a rate determining step?
It is the slowest step of the reaction.
12. What is the difference between homogeneous catalysts and heterogeneous
catalysts?
Homogeneous cat. = same phase as reactants Ex: H2O2
Heterogeneous cat. = different phase from reactants and contains adsorption,
then absorption.Ex: C2H4 (Ethylene) or Al2O3 (Alumina) or HCOOH (Formic Acid)
13. A reaction obeys the following rate law: Rate = k[B]2
A+B C
a) if [A] is doubled, how will the rate change? Explain
b) what are reaction orders for A and B? What is the overall reaction order?
c) what are the units of k for this reaction?
a. If A is doubled there will be no change in the rate constant as it does not
include A and the rate constant only changes with time. ∆T
b. the reaction order [A] = 0, reaction order [B] = 2, over all reaction order = 2.
c. units of k = M/s = M-1s-1 change per reaction.
M2
14. The gas phase decomposition of SO2Cl2, SO2Cl2  SO2 (g) + Cl2 (g) is 1st
order in SO2Cl2. At 600K the half life for this process is 2.3x105s. A. What is the
rate constant at this temperature? B. Calculate the half life if the rate constant is
2.2x10-5s-1 at 320°C.
A. t1/2 = 2.3x105s; t1/2 = 0.693/k  k = 0.693/t1/2 k = 0.693/3x105s = 3.0x10-6s-1
B. k = 2.2x10-5s-1; t1/2 = 0.693/2.2x10-5s-1  3.15x104s = t1/2