Question

For the reaction 2A + B = 2C + , the following data were measured at 100 C.

Experiement #	Inital [A] (mol/L)	Initial [B] (mol/L)	Initial Rate (mol/L*min)
1	0.300	0.150	3.58 * 10 ^ -3
2	0.500	0.150	6.01 * 10 ^ -3
3	0.300	0.350	1.91* 10 ^ -2

a) What is the order of the reaction?

b) Calculate the rate constant and indicate its units

Answer 1

a)
see experiment 1 and 2:
[A] becomes 0.500/0.300 = 1.67 times
[B] is constant
rate becomes 6.01/3.58 = 1.67 times
so, order of A is 1

see experiment 1 and 3:
[A] is constant
[B] 0.350/0.150 = 2.33
rate becomes 19.1/3.58 = 5.34 times

since 2.33^2 = 5.34
so, order of B is 2

overall order = 1 + 2 = 3
Answer: 3

b)
Rate law is:
rate = k*[A]*[B]^2

Put values from 1st row of table in rate law
rate = k*[A]*[B]^2
3.58*10^-3 = k*0.3*0.15^2
k = 0.5304 M-2.s-1
Answer: 0.530 M-2.s-1