Question

The half-equivalence point of a titration occurs half way to the end point, where half of the analyte has reacted to form its conjugate, and the other half still remains unreacted. If 0.580 moles of a monoprotic weak acid (Ka = 4.5 _ 10-5) is titrated with NaOH, what is the pH of the solution at the half-equivalence point?

Answer 1

The only thing you need to know to find  pH of the solution at the half-equivalence point is to remember that  pH is always equal to pKa, therefore you can easily get ehat you need - 4.35.