Question

A reaction that is first order with respect to reactant A has a rate constant of 6 min⁻¹. If we start with [A] = 50 mol L⁻¹, when would [Al reach the value of 0.05 mol L⁻¹?

Answer 1

Given:

First-order reaction

Rate constant: k = 6 min⁻¹

Initial concentration: [A]₀ = 50 mol L⁻¹

Final concentration: [A] = 0.05 mol L⁻¹

By using integrated rate law for first-order reactions

`t = 2.303/k log ([A]_0/([A]))`

= `2.303/6 log (50/0.05)`

= `2.303/6 log(1000)`

= `(2.303 xx 3)/6`

= `6.909/6`

t = 1.15 minutes