Hey guys! I would appreciate if someone could describe the common-ion effect to me in lamens terms, I've been trying to learn it but I just don't seem to understand it.

Question

anonymous · Answer

Do you by any chance understand, or at least have a basic grasp on Le Châtelier's Principle?

anonymous · Answer

If a system at equilibrium resists change (Le Châtelier's Principle) then the addition of an already present species (your common ion) is going to affect that equilibrium.
Or even more simply, if you have two sources with a common ion that is going to be involved in some sort of reaction (usually precipitation) then when you add the secondary source of the common ion to the reaction it will lower the solubility of the other product already involved in the equilibrium.