AP Chem Titration problem

Test Preparation AP Test Preparation
1

<p>Ok so the university that hosts the labs for AP chem is doing a lab on titration... which we covered weeks ago in class. Now I have to do this prelab that I really don't understand.
Heres the question that really throws me for a loop.
A 3.0975g sample of a mixture of mercaptoacetic acid and KCl was disolved in pure water and titrated to equivalence point. The formula for mercaptoacetic acid is H2C2H2O2S, which is diprotic. The titration required 41.83 ml of a .1135 M NaOH solution.
a) write a balanced equation for the reaction.
b) How many moles of mercaptoacetic acid were titrated?
c) What was the original mass of mercaptoacetic acid in the sample?
d) What percent of the sample was mercaptoacetic acid?</p>

<p>Any help on this one would be highly appreciated, Thanks!</p>

2

<p>anyone? anyone at all?</p>

3

<p>diprotic means it has two transferrable protons, so I think the equation is:</p>

<p>H2C2H2O2S + 2NaOH = Na2C2H2O2S +2HOH</p>

<p>That makes the rest easy, correct?</p>

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<p>^yeap.....</p>