A first order reaction taken 16 minutes for 50% completion. How much time will it take for 75% completion ?

Explanation

Case I :
t=16 min
`therefore k=(0.693)/(t_(1//2))=(0.693)/("16 min")=0.433" min"^(-1)`
Case II :
`[R]_0=100(say)`
[R]=100-75=25
t=?,k=09.0433 `min^(-1)`
`t=(0.693)/("16 min")log([R]_0)/([R])`
`=(2.303)/(0.433min^(-1))log(100)/(25)`
`=(2.303xxlog4)/(0.0433min^(-1))`
`=(2.303xx0.6021 min)/(0.433)`
=32.024 min