A 125 mL sample of phosphoric acid was titrated with an average of 63.7 mL of a 0.050M barium hydroxide solution according to the given reaction: 2 H3PO4 + 3 Ba(OH)2 ⇌ Ba3(PO4)2 + 6 H2O Determine the concentration of the phosphoric acid sample:

0.017 M

Explanation:

The balanced equation for the reaction is given below:

2H₃PO₄ + 3Ba(OH)₂ ⇌ Ba₃(PO₄)₂ + 6H₂O

From the balanced equation above,

The mole ratio of acid, H₃PO₄ (nₐ) = 2

The mole ratio of base, Ba(OH)₂ (n₆) = 3

Finally, we shall determine the concentration of the phosphoric acid, H₃PO₄. This can be obtained as follow:

Volume of acid, H₃PO₄ (Vₐ) = 125 mL

Volume of base, Ba(OH)₂ (V₆) = 63.7 mL

Concentration of base, Ba(OH)₂ (C₆) = 0.050M

Concentration of acid, H₃PO₄ (Cₐ) =?

CₐVₐ / C₆V₆ = nₐ/n₆

Cₐ × 125 / 0.05 × 63.7 = 2/3

Cₐ × 125 / 3.185 = 2/3

Cross multiply

Cₐ × 125 × 3 = 3.185 × 2

Cₐ × 375 = 6.37

Divide both side by 375

Cₐ = 6.37 / 375

Cₐ = 0.017 M

Thus, the concentration of the phosphoric acid, H₃PO₄ is 0.017 M