Question

The electrodes of a conductivity apparatus are placed in a beaker with 25 ml of 0.01 M sulfuric acid and then this acid is titrated with 0.01 M barium hydroxide. Barium sulfate is formed as the titration is performed. The electrodes are kept submerged in the beaker for the entire titration. Which of the following statements, I-IV, is/are true?

I. The bulb of the conductivity apparatus will glow brightly when 45 ml of barium hydroxide is added.

II. When moles of base equals moles of acid during the titration, there are large quantities of barium and sulfate ions in solution.

III. The bulb of the conductivity apparatus will glow brightly when 25 ml of barium hydroxide is added.

IV. When moles of base equals moles of acid, an electrolyte is formed.

A. I only
B. II only
C. I and III
D. II and IV
E. I, III and IV

Answer 1

A. I only is the answer.

25 mL of 0.01 M sulfuric acid will be neutralised with 25 mL of 0.01 M barium hydroxide.

I. The bulb of the conductivity apparatus will glow brightly when 45 ml of barium hydroxide is added.

At this point, large excess of base is present. Barium hydroxide is strong base and will completely dissociate in aqueous solution in ions.

II. When moles of base equals moles of acid during the titration, a precipitate of barium sulphate is formed. Barium sulfate is sparingly soluble in water and very few barium and sulfate ions will be present in solution.

III. The bulb of the conductivity apparatus will glow dimly when 25 ml of barium hydroxide is added. This is equivalence point where all sulfuric acid is completely neutralised with barium hydroxide and sparingly soluble barium sulfate is formed. Very few ions are present in the solution.

IV. When moles of base equals moles of acid, a non electrolyte is formed. This is equivalence point where all sulfuric acid is completely neutralised with barium hydroxide and sparingly soluble barium sulfate is formed. Very few ions are present in the solution.