Question

The rate constant for a first order reaction is 7.0 $\times$ ${10}^{-4}$ $s^{-1}$. If the initial concentration of the reactant is 0.080 M, what concentration will remain after 35 minutes?

Answer 1

The concentration of the reactant at any time $t$ is given by,

$A_t=A_o{e}^{-kt}$

GIven,

$A_o=0.080M$

$t=35\times 60=2100s$

$k=7\times {10}^{-4}{s}^{-1}$

Hence,

$A_t=0.080e^{-7\times {10}^{-4}\times 2100}$

$A_t=0.0184M$