Question

Higher yield of NO in the reaction
N$_2$ (g) + O$_2$ (g) $\rightarrow$ 2NO (g)
can be obtained at [$\Delta H$ of the reaction = +180.7 kJ mol$^{-1}$]

• A. B, C only
• B. B, C, D only
• C. A, C, D only
• D. A, D only

Hint:

For endothermic reactions, higher temperatures and increased concentrations of reactants will favor the formation of products, according to Le Chatelier's principle.

Answer 1

The Correct Option is C

For the reaction: \[ \text{N}_2 (g) + \text{O}_2 (g) \rightarrow 2 \text{NO} (g) \] The reaction is endothermic (\(\Delta H>0\)). Applying Le Chatelier's Principle: - A. Increased temperature: As the reaction is endothermic, a higher temperature will shift the equilibrium to the right, favoring NO production. Therefore, higher temperatures enhance NO yield. This statement is correct. - B. Decreased temperature: Lowering the temperature will shift the equilibrium to the left, favoring the reactants. Consequently, lower temperatures will not increase NO yield. This statement is incorrect. - C. Increased N\(_2\) concentration: An increase in reactant concentration (N\(_2\)) drives the equilibrium to the right, producing more products. This statement is correct. - D. Increased O\(_2\) concentration: Similarly, increasing O\(_2\) concentration shifts the equilibrium to the right, increasing NO yield. This statement is correct. Therefore, the correct options are A, C, and D.