Question

The thermal decomposition of a compound is of the first order. If 50% of the sample is decomposed in 120 minutes, how long will it take for 90% of the compound to decompose?

Answer 1

Half life of the reaction = 120 min.

We know that

\(k = \frac{0.693}{t_{1/2}} = \frac{0.693}{120}\)

If a = 100, x = 90, a-x = 10

= 5.77 x 10^-3 min^-1

Applying first order rate equation.