Chemistry - Chemical Kinetics Question with Solution | TestHub

Key Idea Rate of disappearance of reactant $=-\frac{1}{\text{ stoichiometry }}\times \frac{\text{ change in conc of reactant }}{\text{ time taken }}$ coefficient of the reactant Rate of appearance of product change in conc $=\frac{1}{\text{ stoichiometry coefficient }}\times \frac{\text{ of product }}{\text{ time taken }}$ For the reaction, $$\begin{array}{rl}& {\mathrm{N}}_2+3{\mathrm{H}}_2⟶2{\mathrm{NH}}_3\\ & \begin{array}{rl}& \text{ Rate }=-\frac{\mathrm{d}\left[{\mathrm{N}}_2\right]}{\mathrm{dt}}=-\frac{1}{3}\frac{\mathrm{d}\left[{\mathrm{H}}_2\right]}{\mathrm{dt}}=+\frac{1}{2}\frac{\mathrm{d}\left[{\mathrm{NH}}_3\right]}{\mathrm{dt}}\\ & \text{ or }-\frac{1}{3}\frac{\mathrm{d}\left[{\mathrm{H}}_2\right]}{\mathrm{dt}}=+\frac{1}{2}\frac{\mathrm{d}\left[{\mathrm{NH}}_3\right]}{\mathrm{dt}}\\ & -\frac{\mathrm{d}\left[{\mathrm{H}}_2\right]}{\mathrm{dt}}=\frac{3}{2}\times 2\times 10^{-4}\mathrm{mol}{\mathrm{L}}^{-1}{\mathrm{s}}^{-1}\\ & =3\times 10^{-4}\mathrm{mol}{\mathrm{L}}^{-1}{\mathrm{s}}^{-1}\end{array}\end{array}$$