Question

For a reaction $2X\left(g\right)+2Y\left(g\right)\iff Z\left(g\right)+80Kcal$, which combination of pressure and temperature gives the highest yield of $Z$ at equilibrium?

• A. $1000atm$ and ${500}^{\circ }C$
• B. $500atm$ and ${500}^{\circ }C$
• C. $1000atm$ and ${100}^{\circ }C$
• D. $500atm$ and ${100}^{\circ }C$

Answer 1

Answer: (C)

$1000atm$ and ${100}^{\circ }C$

The reaction $2X\left(g\right)+2Y\left(g\right)\iff Z\left(g\right)+80Kcal$ is favored in the forward direction at high pressure and low temperature.
The forward reaction proceeds with decrease in the number of moles from $4$ to $1$. When the pressure is increased by decreasing the volume at constant temperature, the forward reaction will be favored. The forward reaction is also an exothermic reaction as heat is liberated during the reaction. When temperature is lowered, the reaction will proceed in the forward direction so as to liberate heat and nullify the effect of lowering temperature.

Hence, option c will be the correct answer having maximum pressure and minimum temperature.