posted by james .
A 0.446 g- sample of an unknown monoprotic acid was titrated with 0.105 M KOH. the molar mass is 120 g/mol What is the pKa value?
Is this all of the information you have? I think you need the pH at SOME point, or a way to calculate pH at the beginning or the end and I don't see a way to do it without other information. The usual way is to calculate moles of the acid (moles = grams/molar mass) and use that information to calculate mL of KOH to the equivalence point, then take 1/2 that amount and the pH = pKa. To do this, however, one must have a way to calculate the pH at that point.
Yes, there is a titration curve that goes with this problem.