Given that
The diprotic acid has the
and
.
The concentration of acid, C = 0.124 M
The first equivalence point means KOH neutralizes half of the H+ ions in acid. At this point
The number of moles of H+ ion = molarity * volume
= 0.124M * 0.019 L
= 0.00236 mol
Hence the number of moles of KOH required to get the first equivalence point = 0.00236 mol
Give that
The molarity of KOH = 0.1017 M
The volume of KOH required = number of moles of KOH / molarity
= 0.00236 mol / (0.1017 mol/L)
= 0.0232L
= 23.2 mL