Consider a certain reaction `A rarr` Products with `k=2.0xx10^(-2)s^(-1)`. Calculate the concentration of `A` remaining after `100s` if the initial concentration of `A` is `1.0 mol L^(-1)`.

Explanation

`k = 2.0xx10^(-2) s^(-1)`
`T = 100s`
` [A]_(0)=1.0mol^(-1)`
Since the unit of k is `s^(−1)`, the given
reaction is a first order reaction.
`implies 2.0xx10^(-2)s^(-1)=(2.303)/(100s)"log"(1.0)/[A]`
`implies 2.0xx10^(-2)s^(-1)=(2.303)/(100s)(-"log"[A])`
`implies -log[A]= (2.0xx10^(-2)xx100)/(2.303)`
`implies [A]= anti"log"(-(2.0xx10^(-2)xx100)/(2.303))`
`0.135"mol"L^(-1)` (approximately)
Hence, the remaining
concentration of A is` 0.135 "mol"^(-1)`