- #1

Maharg

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## Homework Statement

Consider 1L of a solution that is 0.100 M in acetic acid and 0.100 M in sodium acetate. What will the pH be, when 0.0900 mol of sodium acetate are added?

Ignore changes in volume.

acetic acid pka = 1.75 E-5

## Homework Equations

HA --> H+ + A-

pH=pka +log A-/HA

## The Attempt at a Solution

I had similar questions that I know how to do with strong acids. The difference in this question is that the added acid/base is a weak one. With the strong base addition I can just add it to A- concentration and subtract it from HA and use Henderson-Hasselbach equation.

This one I tried that but the numbers I know are off. I also tried doing ka = H+*(0.1+.009)/0.1

Solving for H+ and then using that to find out concentrations of A- and HA but the H+ number is far too small to make a difference and I'm fairly sure I can't just add the conjugate bases together.

Can someone please help.