Question

By what factor does the rate change in each of the following cases (assuming constant temperature)?

Factor (enter as decimal if <1)
(a) A reaction is first order in reactant A, and [A] is doubled.
(b) A reaction is second order in reactant B, and [B] is halved.
(c) A reaction is second order in reactant C, and [C] is tripled.

Answer 1

a) The rate of reaction increases by factor of 2.

b) The rate of reaction increases by factor of 0.25.

c) The rate of reaction increases by factor of 9.

Step-by-step explanation:

a)

Rate of the reaction ;

`R=k[A]^1`

if [A] is doubled, then rate of the reaction = R'

`R'=k[2A]^1`

`R'=2k[A]`

`R'=2R`

The rate of reaction increases by factor of 2.

b)

Rate of the reaction ;

`R=k[B]^2`

if [B] is halved, then rate of the reaction = R'

`R'=k[(B)/(2)]^2`

`R'=(1)/(4)k[B]^2`

`R'=0.25R`

The rate of reaction increases by factor of 0.25.

c)

Rate of the reaction ;

`R=k[C]^2`

if [C] is tripled, then rate of the reaction = R'

`R'=k[3C]^2`

`R'=9k[C]^2`

`R'=9R`

The rate of reaction increases by factor of 9.