Question

In a reaction, if the concentration of the reactant R is quadrupled, the rate of

reaction becomes sixty four times. What is the order of reaction?
​

Answer 1

Answer:

then order of reaction must be three

Answer 2

Given: the concentration of reactant, [r] = A and [r₁]= 4A

           the rate of reaction, R and R₁ = 64R

To Find: the order of the reaction, n.

Solution:

To calculate n, the formula used:

• R = k [r]ⁿ                                                   ⇒ Rate Law

        here R is the rate of reaction

        k is the rate constant

        [r] is the concentration of reactant

        n is the order of the reaction

Applying the above formula when rate of reaction R and [r] is A:

R  = k [ A ]ⁿ                                ⇒ 1

For R₁  and  [r₁] :

R₁  = k [ r₁ ]ⁿ                                ⇒ 2

64 R = k [ 4A ]ⁿ

On dividing equations 1 and 2:

R / 64 R  = k [ A ]ⁿ  / k [ 4A ]ⁿ

1 / 64      =   [ A ]ⁿ /  [ 4A ]ⁿ

1 / 64      =   [ A ]ⁿ / 4ⁿ x  [ A ]ⁿ

1 / 64      =  1 / 4ⁿ

Taking reciprocal on both the side:

64   = 4ⁿ

4ⁿ    = 64

4ⁿ    = 4³

∴ n = 3

Hence order of the reaction is three.