Yep, by pure liquids, I meant adding reagants like the H2SO4 you mentioned, I'm just wondering, won't it react with a particular side of the equilibrium and thus cause a shift?
Also with adding just normal water to the equilibrium, am I correct to assume that since it's just water, the dilution it causes to both sides of the equilibrium is equal and thus it will overall have no effect on the equilibrium, similar to how a catalyst, when added, simply speeds up the rate of reaction and has no overall effect on the equilibrium?
Ok I had to do a bit of research to determine a formal answer.
The whole basis of Le Chatelier's Principle and all factors of dynamic equilibrium do not strictly relate to the moles of the substance, rather, the concentrations of the substances.
Effectively, gas concentrations can be measured as they will essentially be the moles of the substance over the volume of the vessel.
An aqueous substance's concentration can also be measured as it is the moles of the substance over the volume of the entire fluid they're dissolved in.
Solids and liquids, on the other hand, cannot be defined in terms of a concentration. You can add more moles of solid or liquid to a system, but this doesn't change their concentrations. The reason for this is, what is there to change the concentration with respect to?
- For solids, just adding more of them in really doesn't do much. They'll just sit there.
- For liquids, if you add more liquid what can you take the concentration of liquid with respect to? You increase the moles of the liquid, but you don't have something to take a volume with respect of, to find a concentration.
If your school elects to take up the industrial chemistry option topic, you will also be introduced to the equilibrium constant of a system, and find that in this constant (determines the ratio of reactants to products) no solid or liquid is included either.