Question

A reaction is 20 % complete in 20 min . Calculate the time required for 80 % completion of reaction
, If reaction follows the first order .

Answer 1

Answer:

PSP

Explanation:

For first order reaction we have:-

K=  

t

1

​  

ln(  

a−x

a

​  

)           −(i)

where, K= rate constant

            t= time

            a= initial concentration of the reactant

            x= amount of reactant reacted in time t

Case I: t=20 min

x=  

100

20

​  

×a⇒x=0.2a    (∵20 % reaction is complete)

⇒ a−x=0.8a

Answer 2

Answer:

20 % require 20 min means 1 % require 1 min , then 80% require 80 min