Question

Substance A reacts according to a first order rate law with $5{\times 10}^{-5}{s}^{-1}$.
a) lf the initial concentration of A is 1.0 M, what is initial rate.
b) what is the rate after 1.0 hour. ${(Givene}^{-0.18}=0.84)$

Answer 1

$Rate=k\left[A\right]$

Substituting the values, we get

a) $Rate=1\times 5\times {10}^{-5}$ = $5\times {10}^{-5}M{s}^{-1}$

b )$5\times {10}^{-5}=\frac{2.303}{3600}log\frac{\left[1\right]}{\left[A\right]}$

$\left[A\right]=\frac{1}{0.84}$ = $1.19M$

$Rate=5\times {10}^{-5}\times 1.19$ = $5.95\times {10}^{-5}M{s}^{-1}$