Question: If a first order reaction takes 32 minutes for 75% completion, then time required for 50% completion...

Question

If a first order reaction takes 32 minutes for 75% completion, then time required for 50% completion is :

Answer 1

k = $\frac{2.303}{t}$ log $\left( \frac{a}{a - x} \right)$

When, a = 100, x = 75, t = 32

k = $\frac{2.303}{32}$ log₁₀ $\left( \frac{100}{25} \right)$ = 0.0433 min^–1

Time for 50% completion (t_1/2) = $\frac{0.693}{k}$

= $\frac{0.693}{0.0433}$ » 16 min