# Le Châtelier’s Principle and Addition of Water

With regards to gas volume, Le Châtelier’s principle predicts that an increase in the volume of the container causes the system to favor the side of the reaction that produces more moles of gas. However, would this principle apply equally well to an aqueous system, at equilibrium, that has now had water added to it? That would be analogous to expanding the volume of a gaseous system, wouldn’t it? Would adding water to an aqueous system at equilibrium affect the position of equilibrium at all?

• It is not exactly analogous to expanding the volume, but adding water affects the concentrations of both the reactants and products, which in turn affects the position of equilibrium. Nov 16, 2015 at 17:40
• Nov 17, 2015 at 3:24

Yes adding more water will affect the position of the equilibrium simply because you are adding more volume to the solution by adding more water. So adding volume is inversely proportional to pressure where the system needs to reduce the amount of water. Then the equilibrium will shift to the side with increased amount of pressure.

• We are talking about liquids here, not gases, so volume is not inversely proportional to pressure. In fact, pressure is not really relevant at all.
– bon
Apr 28, 2016 at 16:26
• It will not be liquid as a whole because we add water to a system which is already aqueous. So this results in an aqueous system again. If it is either gas or liquid it definitely has no link to the equilibrium constant for sure. And as the Boyle's law states, pV = nRT, it is clear that pressure is inversely proportional to temperature. The volume will impact on the pressure and the pressure will decide which way should the system shift, in relevence to the coefficients of the products and reactants. Apr 29, 2016 at 5:46
• pV=nRT only applies to a gas, not a liquid.
– bon
Apr 29, 2016 at 7:34
• Yeah true. That's why I stated that liquid or solid could not be considered when calculating the equilibrium constant which implies the meaning that Boyle's law has nothing to do with liquid or solid. Apr 29, 2016 at 8:20
• But the entire question is only about solutions so any discussion of gas laws is irrelevant.
– bon
Apr 29, 2016 at 9:06