Question

A substance '$A$' was found to undergo two parallel first order reactions, i.e., $A\to B$ and $A\to C$, with rate constants $1.26\times {10}^{-4}{s}^{-1}$ and $3.8\times {10}^{-5}{s}^{-1}$ respectively. What were the percentage distribution of $B$ and $C$?

Answer 1

$K_{1}A\to B{K}_2\downarrow C$

We know $\frac{\left[B\right]}{\left[C\right]}=\frac{K_1}{K_2}$

Hence %$B=\frac{K_1}{K_1+K_2}\times 100=\frac{1.26\times {10}^{-4}}{1.26\times {10}^{-4}+3.8\times {10}^{-3}}\times 100=3.2$%

Hence %$C$$=100-3.2=96.79$%