Textbook Problem

A reaction generates chlorine gas $\left({\text{Cl}}_{\text{2}}\right)$ as a product. The reactants are mixed and sealed in a $\text{250}\text{.-mL}$ container. After $\text{30}\text{.0}\text{minutes}$, $2.97\times {10}^{-2}\text{mol}$ of ${\text{Cl}}_{\text{2}}$ has been generated. Calculate the average rate of the reaction.