The rate constant of a first order reaction is `4.5 xx 10^(-2) sec^(-1)` What will be the time required for the initial concentration of 0.4 M of the reactant to be reduced to 0.2 M ?

Explanation

`k= 4.5 xx 10^(-2) s^(-1)`
Since the initial concentration is to be reduced to one half, the time required will be equal to half life period, `t_(0.5)`. For a first order reaction,
` t_(0.5 ) = ( 0.693 )/(k) = ( 0.693)/( 4.5 xx10^(-2)) sec = 15.4 sec`
Therefore, time required to reduce the initial concentration of 0.4 M to 0.2 M is 15.4 sec.