KCET 2025 Chemistry Paper

To determine the rate of production of $\mathrm{NO}_2$ for the reaction $2\,\mathrm{N}_2\,\mathrm{O}_{5(\mathrm{g})} \longrightarrow 4\,\mathrm{NO}_{2(\mathrm{g})}+\mathrm{O}_{2(\mathrm{g})}$, we use the fact that the rate of production of a product is related to the rate of disappearance of a reactant.Given:Initial concentration of $\mathrm{N}_2\,\mathrm{O}_5$ is $2.0\,\mathrm{mol/L}$.After 300 minutes, the concentration is reduced to $1.4\,\mathrm{mol/L}$.Calculate the rate of disappearance of $\mathrm{N}_2\,\mathrm{O}_5$ : Rate of disappearance of $\mathrm{N}_2\,\mathrm{O}_5=\; \frac{-(1.4-2.0)}{300} =\; \frac{-(-0.6)}{300} =\; \frac{0.6}{300}$As per the stoichiometry of the reaction, the rate of formation of $\mathrm{NO}_2$ is twice the rate of disappearance of $\mathrm{N}_2\,\mathrm{O}_5$ :Rate of formation of $\mathrm{NO}_2 = 2 \times \frac{0.6}{300} = \frac{1.2}{300} = 4 \times 10^{-3}\,\mathrm{mol/L/min}$Therefore, the rate of production of $\mathrm{NO}_2$ is $4 \times 10^{-3}\,\mathrm{mol/L/min}$.