[aaaaaa]

 What quantity (moles) of NaOH must be added to 1.0 L of 
2.0 M HC2H3O2 to produce a solution buffered at each pH?
 a. pH = pKa
 b. pH = 4.00
 c. pH = 5.00

I don't understand how to solve this. I started by finding the value of the ph for the then finding the pOH and then finding the concentration of the pOH but this answer seem to be wrong. I check the manual answers and my answer doesn't match. I think I'm supposed  to assume that the concentration for the acid and the conjugate base is the same and that they add up to be 2M as suggested in the problem therefore the conjugate base would be 1, since there's a 1:1 molar ratio OH would have the same concentration and the same amount of moles. I just don't understand why the first procedure that I used doesn't work and I also don't understand why the acid and the conjugate base should be equal to 2 since this is the concentration given for only the acid ??

Thank you

[Borek]

HC2H3O2

It is not clear what this intended to be. Acetic acid probably, but written in a way designed to be confusing.

a. pH 5 pKa
 b. pH 5 4.00
 c. pH 5 5.00

These numbers don't make much sense, please copy them correctly and we will start from there.

I started by finding the value of the ph for the

For the what?

[Hunter2]

The key is Hendersson Hasselbalch equation.
Check this.