The titration of 80.0 mL of an unknown concentration H3PO4 solution requires 126 mL of 0.218 M KOH solution. What is the concentration of the H3PO4 solution (in M) ?

Ca = 0.1145M

Explanation:

Volume of Acid (Va) = 80.0ml

Concentration of acid (Ca) = ?

Volume of base (Vb) = 126ml

Concentration of base (Cb) = 0.218M

The balanced chemical equation is given as;

3KOH + H3PO4 - -> K3PO4 + 3H2O

The formular relaing the parameters is given as;

(CaVa) / (CbVb) = Na/Nb

Where Na = Number of moles of Acid = 1

Nb = Number of moles of Base = 3

Making Ca subject of interest;

Ca = (Na * Cb * Vb) / (Nb * Va)

Ca = (1 * 0.218 * 126) / (3 * 80)

Ca = 27.468 / 240

Ca = 0.1145M