Question

A first order reaction has a rate constant 0.00813 min^-1. How long will it take for 60% completion?

Options

• 56.35 min

• 98.7 min

• 62.77 min

• 112.7 min

Answer 1

112.7 min

Explanation:

Given,

Rate constant (k) = 0.00813 min^-1

According to first order reaction, the relation is

t = `2.303/"k" log  "a"/("a - x")`

As, a = 100, (a - x) = 100 - 60 = 40

∴ t = `2.303/0.00813 log  100/40`

`= 2.303/0.00813 xx log 2.5`   ...[log 2.5 = 0.3979]

= 112.7 min