PH changes in CH3COOH solution

Question

I have CH3COOH(aq) at pH 4.6. Once addition of NaCl(aq), pH become 4.5. Anyone can explain why pH decreased instead of supposely increase since adding more basic components?

Answer 1

NaCl is a neutral salt and then adding it in solution does not alter the pH

However, if we use the activities instead of concentrations, we must consider the effect that salt

when you add to a solution of a weak electrolyte (as CH3COOH) a strong electrolyte (NaCl) who is not ions in common with the first, increases the ionic strength of the solution and this promotes the dissociation of further weak electrolyte

which is why the pH decreases:  other acid dissociates