Asked by Jim

How do i calculate the pH when 200ml of .200M HCl is added .4998M of sodium acetate?

Answers

Answered by DrBob222
This problem reads suspiciously like something is missing. ......of 0.200 M HCl is added <b>something here</b> .4998 M socium acetate. I don't know how much sodium acetate you have.
Answered by Jim
sorry huge typo
How do i calculate the pH when 200ml of .200M HCl is added to 200.0 ml of .4998M of sodium acetate?
Answered by DrBob222
<b>THANK YOU</b>. I've been looking at this thing, of and on, for over an hour. Even tried some dry runs to see it might work out if I simply assumed a volume of sodium acetate. Of course, none of them would pan out because it made a difference in how much I assumed. SO,
let's call sodium acetate NaAc and the acetate ion Ac^-. Helps on typing.

Ac^- + H^+ ==> HAc (acetic acid)

initial:
Ac^- = M x mL = 0.4998 x 200 mL = 99.96 millimoles.
H^+ = M x mL = 0.2 x 200 mL = 40 mmoles.
HAc = 0 mmoles.

final:
HAc = 40 mmoles.
H^+ = 0
Ac^- = 99.96-40 = 59.96

(Ac^-) = mmols/mL (or moles/L)
(HAc) = mmols/mL (or moles/L)
Substitute into HH equation. Base is Ac^- and acid is HAc.
I get something like 4.9 or so but that's just a close estimate. You need to do it more accurately. By the way, the mL in the concn conversion is 400 mL.

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