Posted by Helen on .
A volume of 25.0 ml of 0.100 M CH3C02H is titrated with 0.100 M NaOH. What is
pH after the addition of 12.5 ml of NaOH? (Ka for CH3CO2H = 1.8x105)

Chemistry 
DrBob222,
Use the HendersonHasselbalch equation. However, you will note that the acid is exactly half neutralized; therefore, the base and acid terms will cancel to leave 1, the log of 1 is zero and pH = pKa for an answer but you work it out to see.