Question

Does Q for the formation of 1 mol of NO from its elements differ from Q for the decomposition of 1 mol of NO to its elements? Explain and give the relationship between the two Q’s.

Short answer

The answer is,

Yes, the reaction quotient in the case of the formation of NO is the reciprocal of the reaction quotient in the case of decomposition of NO.

Step-by-step solution

Reaction quotient

The Reaction quotient of a chemical reaction at a particular point of time at a constant temperature is the ratio of the concentration of the products to that of the reactants raised with the stoichiometry of the compounds in the chemical equation of the reactions.

Explanation

The chemical equation for the formation of 1 mol of NO from its elements is given below.

$\frac{1}{2}{\mathrm{N}}_2+\frac{1}{2}{\mathrm{O}}_2\rightleftharpoons \mathrm{NO}$

Then the reaction quotient is given below.

$Q=\frac{\left[NO\right]}{{\left[N_2\right]}^{1/2}{\left[O_2\right]}^{1/2}}$

The chemical equation for the decomposition of 1 mol of NO to its elements is given below.

$\mathrm{NO}\rightleftharpoons \frac{1}{2}{\mathrm{N}}_2+\frac{1}{2}{\mathrm{O}}_2$

Then the reaction quotient is given below.

$\mathrm{Q}=\frac{{\left[{\mathrm{N}}_2\right]}^{1/2}{\left[{\mathrm{O}}_2\right]}^{1/2}}{\left[\mathrm{NO}\right]}$

The reaction quotient for the formation and decomposition of NO is different. The reaction quotient in the case of the formation of NO is the reciprocal of the reaction quotient in the case of decomposition of NO.