A first order reaction is 15% complete in 20 minutes. How long will it take to complete 60%?

Explanation

`k = (2.303)/(t) "log" ([A]_0)/([A])`
First Order Equation, `[A_0] = 100 `
`[A] = 100 – 15 = 85`
`k = (2.303)/(20) "log" 100/85`
`k = (2.303)/(20) xx 0.0706 = 8.13 xx 10^(-3) "Min"^(-1)`
In second case
`[A]_0 =100 `
`[A] = 100 – 60 = 40 `
`k = (2.303)/(8.13 xx 10^(-3)) "log" 100/40`
`t = (2.303)/(8.13 xx 10^(-3)) xx 0.3979 `
`t = 112.7 `min.