Solids and Liquids in K Expression

[Tiffany_Cacy_3D]

So if you have a chemical equation that you want to find the equilibrium constant for, you do not include solids or liquids at all? I understand that this means that you do not include them in the K equation but if they are a part of the reaction shouldn't they affect the equilibrium? I am just a little confused on why they are excluded and why they don't contribute to finding the equilibrium constant.

[Olivia L 4E]

They are exclude because the equilibrium constant describes concentrations/partial pressures whereas solid has neither. Liquids have a concentration but act as a solvent so they aren't included. Aqueous solutions on the other hand, are the solute so they are included because they are a by-product.

[Tiffany_Cacy_3D]

Thank you that is actually very helpful!