A first order reaction has a specific reaction rate of `10^(-3) s^(-1)`. How much time will it take for `10 g` of the reactant to reduce to `2.5 g`. (Given `log4 = 0.6021`).

Explanation

We know that for a first order reaction
`t = (2.303)/(k)log.(a)/(a-x)`
Here, initial concentration `a = 10 g` and concentration left after time `t s = 2.5 g`
i.e., `(a-x) = 2.5 g`,
Specific reaction conctant `k = 10^(-3) s^(-1)`
`:.` Time required for the reactant to reduce to `2.5 g`
`= (2.303)/(10^(-3)) xx log4 = (2.303)/(10^(-3)) xx 0.6021` (Given `log 4 = 0.6021`)
`= 1386.6 s`