A first order reaction takes 60 minutes for 75% completion. Determine its half- life.

Explanation

For a first order reaction : `k=(2.303)/(t)log.(a)/(a-x)`
Given : when `t=60"min",x=axx(75)/(100)=0.75a`
`thereforea-x=a-0.75a=0.25a and (a)/(a-x)=(a)/(0.25a)=4`
So , `k=(2.303)/(60)log4=(2.303)/(60)xx0.6020=0.0231"min"^(-1)`
`therefore t_(1//2)=(0.693)/(k)=(0.693)/(0.0231"min"^(-1))=30"min"`