Wipe everything about Cl-
, I have not said a word about it.
I was referring JUST to the fact, that every water solution contains both H+
and their concentrations are connected through Kw
]. No idea where did you get this Cl-
thing - it must be some your misconception that I am not able to understand.
mass: [OH-] + [H+]0 = [H+] + [HS-] + [H2S]
These should be separate mass balances for different substances. Like:
] = [S2-
] + [HS-
] + [H2
which reflects the fact that there is exactly the same amount of sulfide as lead in the solution.
charge:() [H+] + 2[Pb2+] = [OH-] + [HS-] + 2[H2S]
In the charge balance you should use ONLY charged particles. Or was 2[H2
S] just a typo? And Cl-
must be included:
] + 2[Pb2+
] = [OH-
] + [HS-
] + 2[S2-
] + [Cl-
Now, what you can safely omit here is OH-
. Its concentration is much lower that that of the other things and it doesn't play any role in the whole system that we are interested in.