Solvents and Homogenous Equilibrium

[Allie Wilcox]

Reviewing my lecture notes I saw the definition of Homogenous equilibrium (all reactants and products in the same phase) and became confused about reactions that include a solvent, but especially water in liquid form. Dr. Lavelle has said that water is involved in the reaction, though its concentration does not change and is thus not a part of the equilibrium constant. But does that mean that it also doesn't count when we are classifying the equilibrium as homogeneous or heterogeneous? Is it or is it not considered a reactant? Thanks!

[Minh-Anh Pham 1B]

I believe that the different phases (aqueous, liquid, gas, etc) do count when we are classifying the equilibrium as homogeneous or heterogeneous, but in terms of including it in equilibrium, you do NOT include pure solids and pure liquids because the concentration of pure solids and liquids do not really change over the course of a reaction.