Question

The reaction between A and B was investigated by a student who claimed to have obtained the following data:

Trial	[A] (M)	[B] (M)	Rate (M/s)
1	0.273	0.763	2.63
2	0.273	1.526	6.63
3	0.546	0.763	4.18

What reaction orders for A and B, respectively, did the student obtain from the data?

A. 3/2, 5/4

B. 2/3, 4/3

C. 3/4, 2/3

D. 4/3, 1/2

E.

2/3, 1/2

Answer 1

A + B      Product

rate = k [A]^a [B]^b

Comparing trial (1) and (2), keeping the concentration of [A] constant and increasing the concentration of [B] by two times the rate of reaction increases by 2.52 times.

2.52 x rate = k [A]^a [2 B]^b

So,

2^b = 2.52

2^4/3 = 2.52

So, b = 1.33 = 4/3

Comparing trial (1) and (3), keeping the concentration of [B] constant and increasing the concentration of [A] by two times the rate of reaction increases by 1.6 times.

1.6 x rate = k [2 A]^a [B]^b

So,

2^a = 1.6

2^2/3 = 1.6

So, a = 2/3

Hence, the rate of equation is

rate = k [A]^2/3 [B]^4/3

Answer is (B) 2/3, 4/3