CHEMISTRY COMMUNITY

Is water not counted in the chemical equilibrium constant? And if so, is this why liquids are not considered either since their concentrations are approximately water?

Pure liquids (such as the solvent water) are not considered in the k expression since there is such a large excess and the amount used in the reaction is a very small amount, we can say that the concentrations do not change significantly. If the concentrations were used to find the equilibrium constant, the values would cancel out and result in a ratio of 1:1.

How come water is included in the equilibrium constant when it is in the gaseous state? Is it because all gasses are included in the calculation when finding k?

Nicole Elhosni 2I wrote:How come water is included in the equilibrium constant when it is in the gaseous state? Is it because all gasses are included in the calculation when finding k?

Yes, I believe you are correct. It might also be because in this reaction, water is not acting as a solvent and, therefore, be included when calculating the equilibrium constant.

You don't count water in the equilibrium constant as it is a pure liquid, and there is so much of it as a solvent that it doesn't matter the small amount that is lost in a chemical reaction.