Question

The rate of first-order reaction is `1.5 xx 10^(-2) M "min"^(-1)` at `0.5 M` concentration of reactant. The half-life of reaction is
A. `0.383 min`
B. `23.1 min`
C. `8.73 min`
D. `7.53 min`

Answer 1

Correct Answer - B
Differential rate law for a first order reaction is Rate `=k[A]`
Thus,
`k=(Rate)/([A])`
`=(1.5xx10^(-2)molL^(-1)min^(-1))/(0.5M)`
`=3xx10^(-2)min^(-1)`
For a first order reaction
`t_(1//2)=(0/693)/(k)=(0.693)/(3xx10^(-2)min^(-1))`
`=23.1min`