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 given: \[ \text{N}_2 (g) + \text{O}_2 (g) \rightarrow 2 \text{NO} (g) \] The reaction has a positive \(\Delta H\), meaning it is endothermic. According to Le Chatelier's Principle: - A. Higher temperature: Since the reaction is endothermic, increasing the temperature will shift the equilibrium to the right, promoting the formation of NO.
Thus, higher temperature will favor the production of NO. This statement is true. - B. Lower temperature: Lowering the temperature would shift the equilibrium to the left, favoring the reactants.
Thus, lower temperature would not increase the yield of NO. This statement is false. - C. Higher concentration of N\(_2\): Increasing the concentration of one of the reactants (in this case, N\(_2\)) will shift the equilibrium to the right to produce more products. This statement is true. - D. Higher concentration of O\(_2\): Similarly, increasing the concentration of O\(_2\) will shift the equilibrium to the right, increasing the yield of NO. This statement is true.
Thus, the correct answer is (3) A, C, D only.