Calculate the time required for the completion of 90% of a reaction of first order kinetics, `t_(1/2)= 44.1` minutes.

Explanation

Step I: To calculate .k.
`t_(1//2)`=44.1 min
`k=(0.693)/(t_(1//2))=(0.693)/(44.1 min)`
k=0.0157 `min^(-1)`
Step II : To calculate .t.
`[R]_0`=100 (say) [R]=100-90=10
k=0.0157 `min^(-1)`,t=?
`t=(2.303)/(k)log([R]_0)/([R])`
`(2.303)/(0.157 min)log(100)/(10)`
`(2.303)/(0.157 min^(-1))log10`
`=(2.303)/(0.0157 min^(-1))xx1`
=146.7 min.