ACS Chemistry Practice Exam 2026 – The All-in-One Guide to Exam Success!

At equilibrium, the position of the equilibrium can be influenced by several factors, including concentration, temperature, and pressure, depending on the state of the reactants and products involved in the reaction.

When considering the impact of pressure on a reaction, it's essential to recognize how the reaction's states of matter (gas, liquid, or solid) play a role. For reactions that exclusively involve solids, changing the pressure does not affect the position of the equilibrium because the concentrations of solids remain constant regardless of pressure changes. In such cases, solids do not contribute significantly to the equilibrium constant, as their activity is considered to be 1.

On the other hand, altering the concentration of products or reactants can shift the equilibrium according to Le Châtelier's principle. This principle indicates that if the equilibrium of a reaction system is disturbed, the system will adjust to counteract the change and establish a new equilibrium. Temperature changes also influence equilibrium by altering the rates of the forward and reverse reactions, especially for exothermic and endothermic reactions. Using a different solvent can affect solubility, reaction rates, and equilibrium constants, thus influencing the equilibrium position.

Therefore, the condition that does not affect the position of the equilibrium in a solid-only reaction is