Question

If the rate with respect to ${\mathrm{O}}_2$, $\mathrm{NO}$ and ${\mathrm{NO}}_2$ are respectively $\frac{-∆\left[{\mathrm{O}}_2\right]}{∆\mathrm{t}}$, $\frac{-1}{2}\frac{∆\left[\mathrm{NO}\right]}{∆\mathrm{t}}$ and $\frac{+1}{2}\frac{∆\left[{\mathrm{NO}}_2\right]}{∆\mathrm{t}}$ then the corresponding chemical equation is $2\mathrm{NO}+{\mathrm{O}}_2\to 2{\mathrm{NO}}_2$.

• A. True
• B. False

Answer 1

The correct option is A True

• Rate of a chemical reaction: The change in concentration of the reactants or products with respect to time is known as the rate of reaction.
• $\mathrm{Rate}\mathrm{of}\mathrm{reaction}=\frac{\mathrm{Change}\mathrm{in}\mathrm{concentration}\mathrm{of}\mathrm{reactants}\mathrm{or}\mathrm{products}}{\mathrm{Time}\mathrm{interval}}$

$\mathrm{r}=\frac{∆\mathrm{C}}{∆\mathrm{t}}$

• If the rate of reaction is measured with respect to reactants, it is given a negative sign, which indicates the decrease in the concentration of the reactants with time.
• If the rate of reaction is measured with respect to products, it is given a positive sign, which indicates the increase in the concentration of the products with time.
• For a reaction : $\mathrm{A}\to \mathrm{B}$, the rate of reaction $\left(\mathrm{r}\right)$ = $\frac{-∆{\mathrm{C}}_{\mathrm{A}}}{∆\mathrm{t}}$ = $\frac{+∆{\mathrm{C}}_{\mathrm{B}}}{∆\mathrm{t}}$ , where $∆{\mathrm{C}}_{\mathrm{A}}$ is the change in concentration of reactant and $∆{\mathrm{C}}_{\mathrm{B}}$ is the change in concentration of the product.
• While writing the equation for the rate of reaction, the stoichiometric coefficients of reactants and products are also taken into consideration. For a general reaction : $\mathrm{aA}+\mathrm{bB}\to \mathrm{cC}+\mathrm{dD}$

$\mathrm{r}=\frac{-1}{\mathrm{a}}\frac{∆{\mathrm{C}}_{\mathrm{A}}}{∆\mathrm{t}}$, $\mathrm{r}=\frac{-1}{\mathrm{b}}\frac{∆{\mathrm{C}}_{\mathrm{B}}}{∆\mathrm{t}}$, $\mathrm{r}=\frac{+1}{\mathrm{c}}\frac{∆{\mathrm{C}}_{\mathrm{C}}}{∆\mathrm{t}}$ , $\mathrm{r}=\frac{+1}{\mathrm{d}}\frac{∆{\mathrm{C}}_{\mathrm{D}}}{∆\mathrm{t}}$ , where $∆{\mathrm{C}}_{\mathrm{A}},∆{\mathrm{C}}_{\mathrm{B}},∆{\mathrm{C}}_{\mathrm{C}},∆{\mathrm{C}}_{\mathrm{D}}$ are the changes in the concentrations of A, B, C and D respectively that occur in time $∆\mathrm{t}$.

• The given rate with respect to ${\mathrm{O}}_2$, $\mathrm{NO}$ and ${\mathrm{NO}}_2$ are respectively $\frac{-∆\left[{\mathrm{O}}_2\right]}{∆\mathrm{t}}$, $\frac{-1}{2}\frac{∆\left[\mathrm{NO}\right]}{∆\mathrm{t}}$ and $\frac{+1}{2}\frac{∆\left[{\mathrm{NO}}_2\right]}{∆\mathrm{t}}$
• Step-1: The negative sign of the rate is shown by the reactant species while a positive sign is shown by the product species.
• Step-2: The reciprocal of the stoichiometric coefficient of the respective reactants and products are multiplied in their rate expression.
• Hence, the corresponding chemical equation is: $2\mathrm{NO}+{\mathrm{O}}_2\to 2{\mathrm{NO}}_2$.
• So, the given statement is true.