ICl(s) + Cl2(g) ⇌ ICl(s) ΔH = -106 kJ mol⁻¹ Which line in the table identifies correctly the changes that will cause the greatest increase in the proportion of solid in the above equilibrium mixture? | Temperature | Pressure | |-------------|----------| | A | decrease | decrease | | B | decrease | increase | | C | increase | decrease | | D | increase | increase | - Scottish Highers Chemistry - Question 20 - 2023

To understand how to increase the proportion of solid ICl in the equilibrium, we need to apply Le Chatelier's principle. Given that the reaction is exothermic (indicated by the negative ΔH value), lowering the temperature shifts the equilibrium to the right, favoring the formation of the solid ICl.

Increasing the pressure generally favors the side of the equilibrium with fewer moles of gas. In this reaction, the left side has 2 moles of gas (1 mole of Cl2 and 1 mole of ICl gas), while the right side has none. Therefore, increasing the pressure also shifts the equilibrium toward the solid ICl, making the changes in option B (decrease in temperature and increase in pressure) the best choice to achieve the desired outcome.