How does I buffer solution?

Here's a kick in the fucking balls (not too hard, really).

A 0.352 g sample of an antacid is dissolved in water. To it is added 40 mL of a 0.141 M HCl solution. The solution is heated to drive off any CO2 gas. It is then back titrated to endpoint with 8.92 mL of a 0.203 M solution of NaOH. How many moles of base were in the original sample of the antacid? How many millimoles?

Will respond with work soon...

I've got your buffered solution right here.

Seems to me that:

number of moles of antacid base + number of moles of OH from NaOH = number of moles of H+ from HCl

You can easily calculate the latter two quantities by multiplying the molarity and the volume, and from that find the number of moles of antacid that should have been added. I don't know why the mass of antacid was given, however.

But it has been a while since I've done these problems, so I could be wrong.