JEE Chemistry 2023 Question with Solution

Given: $2SO_2\text{(g)} + O_2\text{(g)} \rightleftharpoons 2SO_3\text{(g)}$ with $\Delta H = -190 \, \text{kJ}$

Find: The number of factors that increase the equilibrium yield of $SO_3$.

Using Le Chatelier's principle:

• Increasing pressure shifts the equilibrium toward the side with fewer moles of gaseous species. Here, the left side has $3$ moles of gas and the right side has $2$ moles of gas, so the equilibrium shifts to the right.
• Adding more $SO_2$ increases the reactant concentration, so the equilibrium shifts toward products.
• Adding more $O_2$ also increases the reactant concentration, so the equilibrium shifts toward products.

Thus, the factors are B, C, and D.

Therefore, the required number of factors is $3$.

Given: The reaction is

and the process is exothermic with $\Delta H = -190 \, \text{kJ}$.

Find: How many listed factors increase the yield of $SO_3$ at equilibrium.

Check each factor mentioned in the solution:

1. For pressure, compare gaseous moles:

An increase in pressure favors the side with fewer gas moles, so it increases $SO_3$.

2. For adding $SO_2$, increasing a reactant concentration makes the system consume the added reactant by shifting right.

3. For adding $O_2$, the same argument applies; the equilibrium shifts right to form more $SO_3$.

Hence, exactly three factors increase the yield of $SO_3$.

The final answer is $3$.