Question

If 25.0 mL of 0.100 M `HCl` is titrated with 0.150 M `Ba(OH)_2`. what volume of barium hydroxide is required to neutralize the acid?

Answer 1

A little less than half the volume of the starting hydrochloric acid.

Explanation:

We need (i) a stoichiometric equation:

`Ba(OH)_2(aq) + 2HCl(aq) rarr BaCl_2(aq) + 2H_2O`,

Which shows us that 2 equiv acid react with the 1 equiv of barium hydroxide.

And (ii) we need the equivalent quantities of acid and base, observing the stoichiometry.

`"Moles of hydrochloric acid"` `=` `25.00xx10^-3*Lxx0.100*mol*L^-1=2.50xx10^-3*mol`

Given the stoichiometry, this molar quantity represents HALF of the molar quantity of barium hydroxide, which of course had an initial concentration of `0.150*mol*L^-1`. So we take the quotient,

`1/2xx(2.50xx10^-3*mol)/(0.150*mol*L^-1)xx10^3*mL*L^-1~=8*mL`

I have not checked the solubility of the barium salt. Barium hydroxide has limited aqueous solubility. Presumably this question is consistent with experiment.