Problem- If 79.0mL of 0.127 mol/L NaOH(aq) and 50.0mL of 0.189 mol/L HA(aq) are mixed, then what is [HA] at equilibrium? Assume that HA is a weak monoprotic acid with pKa=5.55 at 25oC.
Give reasons or calculations to sustain your answer, please answer with detail step by step.