The elementary reaction $A\to B$ follows first-order kinetics with $k=.01\,\mathrm{min^{-1}}$. Find the batch time to reduce A from 100 M to 10 M, to one decimal place in minutes.
Integrate $dC/dt=-kC$ to obtain $C=C_0e^{-kt}$. Thus $t=\ln(C_0/C)/k=\ln(100/10)/.01=230.2585\ldots$ min. Rounded to one decimal place, the required time is **230.3 min**. The concentration ratio is dimensionless and the rate constant supplies minutes.
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