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Titration of a Weak Acid with a Strong Base

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Find the pH before, at, and after equivalence point of 35 ml of 0.15 M lactic acid with 0.18 M NaOH.

This is all the information I was given on this problem and I am confused.

I think the pKa for lactic acid is 3.86.

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Solution Preview

find the ph before, at, and after equivalence point of 35 ml .15 M lactic acid with .18 M NaOH

This is all the information I was given on this problem and I am confused.

I think the pKa for lactic acid is 3.86...Uggh, I am so confused about this.

The Ka for lactic acid is 1.38 * 10-4. This means the pKa like you said is 3.86.

Before Equivalence Point

Before the titration, the pH is based on the lactic acid. The Ka needs to be used to find [H+].

Ka = [H+][A-] / [HA]

[HA] above is the ...

Solution Summary

This solution shows how to calculate the pH of a titration of 0.15 M lactic acid with 0.18 M NaOH at the following points:

1) Before titration begins
2) At the equivalence point
3) Beyond the equivalence point

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