Question

An aqueous solution of barium hydroxide is standardized by titration with a 0.156 M solution of hydrochloric acid.

If 28.6 mL of base are required to neutralize 25.7 mL of the acid, what is the molarity of the barium hydroxide solution?

Answer 1

ANSWER:

Molarity of hydrochloric acid (Acid) = 0.156 M

Normality of hydrochloric acid (Acid), N₁ = 0.156 N {because it gives 1 H⁺}

Volume of hydrochloric acid (Acid), V₁ = 25.7 mL

Volume of barium hydroxide (Base), V₂ = 28.6 mL

Normality of barium hydroxide (Base), N₂ = ?

At neutralisation point,

N₂V₂ = N₁V₁

N₂ x 28.6 mL = 0.156 N x 25.7 mL

N₂ = 0.140 N

Now, we know that

Normality = n x Molarity {where, n is H⁺/OH^- release or taken by the compound}

In case of barium hydroxide, it gives 2 OH^- ions. So,

Normality = 2 x Molarity

0.140 N = 2 x Molarity

Molarity = 0.070 M

Hence, the molarity of the barium hydroxide solution is 0.070 M.