Cl- Not Included in pH Calculations

[Vy Le 1G]

Hello, in today’s lecture, it was taught that Cl- does not affect pH. I understand that group 1 and 2 elements are not strong enough to dissociate the H proton but why is Cl- not affecting the pH?

[MaiVyDang2I]

Cl- is an anion of a strong acid (HCl), and a strong acid is said to deprotonate/dissociate completely in an aqueous solution so both H+ and Cl- are spectator ions, they don't affect the pH. You can also think of Cl- as an anion of such a strong acid would be a very weak base (low pH = high [H+] = low [OH-]) that they have no significant effects on pH, so they're said to be neutral.