A 250 mL sample of 0723 M HNO3 is titrated with a 027 M KOH

A 25.0 mL sample of 0.723 M HNO₃ is titrated with a 0.27 M KOH solution. The H₃O⁺ concentration after the addition of 80.0 mL of KOH is __________ M.

Solution

Ma = 0.723M

Va = 25 ml

Mb = 0.27M

Vb = 80ml

as Ma*Va < Mb*Vb

after titration [OH-] = Mb*Vb-Ma*Va/(Va+Vb)

[OH-] = 0.034M

so [H+] = 10^-14/[OH-] = 2.97*10^-13