1. OBJECTIVES: RATE LAW, ORDER OF REACTION, k
KINETICS LESSON 4/12/10
OBJECTIVES: RATE LAW, ORDER OF REACTION, k
EXAMPLE: For the reaction below, use the experimental data provided in the table to calculate the rate law and k.
2 NO(g) + Br2(g)  2 NOBr(g)
TRIAL
[NO]
[Br2]
INITIAL RATE
(MOL/Ls) #1
0.10 12 #2
0.20 24 #3
0.30 36 #4 48 #5
108

2. TRIAL
[NO]
[Br2]
INITIAL RATE
(MOL/Ls) #1
0.10 12 #2
0.20 24 #3
0.30 36 #4 48 #5
108
Between experiments 1 and 4 [NO] doubles.
Between experiments 1 and 4 [Br2] is constant.
Between experiments 1 and 4 RATE quadruples factor of 4)
Between experiments 1 and 4 with [Br2] constant and [NO] doubling, the rate quadruples, NO is second order.

3. TRIAL
[NO]
[Br2]
INITIAL RATE
(MOL/Ls) #1
0.10 12 #2
0.20 24 #3
0.30 36 #4 48 #5
108
THE [NO] IS CONSTANT.
THE [Br2] IS DOUBLES.
THE RATE DOUBLES.
Between experiments 1 and 2 [Br2] DOUBLES (and [NO] is constant) as the rate doubles, Br2 is first order.

4. CALCULATE k FROM ANY TRIAL.
RATE = k[NO]2[Br2]
CALCULATE k FROM ANY TRIAL.
RATE = k[NO]2[Br2]
USING TRIAL #1
(12 MOL L-1s-1) =k(0.10 MOL L-1)2(1.0 MOL L-1)
k = 1.2 * 104 L2 /MOL2 s2 (♪NOTE: k has units!)