Phosphoric acid is neutralized by potassium hydroxide according to the following reaction:
KOH + H3PO4 → K3PO4 + H2O
What is the concentration of a phosphoric acid solution if 24.0 mL are exactly neutralized by 16.0 mL of 2.000 M KOH solution? (Note: 1.0 M H3PO4 = 3.0 M H+)

The answer to your question is 1.33 M

Explanation:

Data

Volume of H₃PO₄ = 24 ml

[H₃PO₄] = ?

Volume of KOH = 16 ml

[KOH] = 2 M

1 M H₃PO₄ = 3.0 M H⁺

Balanced chemical reaction

             KOH  +  H₃PO₄   ⇒   K₃PO₄  +  H₂O

Process

1.- Calculate the moles of KOH

Molarity = moles / volume

-Solve for moles

moles = Molarity x volume

-Substitution

moles = 2 x 16/1000

-Simplification

moles = 32/1000

-Result

moles = 0.032

2.- Calculate the moles of H₃PO₄

              1 mol of KOH 1 mol of H₃PO₄

 0.032 moles of KOH     x

                 x = (0.032 x 1) / 1

                 x = 0.032 moles of H₃PO₄

3.- Calculate the concentration of H₃PO₄

Molarity = 0.032 / 0.024

-Result

Molarity = 1.33