Consider the following reaction equation: {N}₂(g)} + 3{H}₂(g)} leftharpoons 2{NH}₃(g)} ; Δ H = -92\,{kJ}. Increasing the temperature of the reaction would

Correct Answer is : decrease the yield of ammonia

shift the equilibrium to the right

decrease the amount of hydrogen

Correct Answer is : decrease the yield of ammonia

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WAEC Chemistry 2022 Paper

Question : 25

Total: 50

\mathrm{N}_{2(g)} + 3\mathrm{H}_{2(g)} \rightleftharpoons 2\mathrm{NH}_{3(g)} ; \Delta H = -92\,\text{kJ}.

Increasing the temperature of the reaction would

Solution:

Concept:

This reaction is exothermic because

\Delta H = -92\,\text{kJ}

is negative.

For an exothermic reaction, heat can be treated as a product.

Explanation:

The equation is:

\mathrm{N}_{2(g)} + 3\mathrm{H}_{2(g)} \rightleftharpoons 2\mathrm{NH}_{3(g)} + \text{heat}

Increasing the temperature adds heat to the system.

According to Le Chatelier’s principle, the equilibrium shifts in the direction that absorbs heat.

So the equilibrium shifts to the left, towards the reactants.

This favours the decomposition of ammonia.

Therefore, the yield of ammonia decreases.

Answer:

The correct option is D: decrease the yield of ammonia.

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