Question

The hydrogen sulfate or bisulfate ion HSO₄⁻ can act as either an acid or a base in water solution. In which of the following equations does HSO₄⁻ act as an acid?

a) HSO₄⁻ + H₂O ⇌ H₂SO₄ + OH⁻
b) HSO₄⁻ + H₃O⁺ ⇌ SO₃²⁻ + 2H₂O
c) HSO₄⁻ + OH⁻ ⇌ H₂SO₄ + O⁻
d) HSO₄⁻ + H₂O ⇌ SO₄²⁻ + H₃O⁺

Answer 1

The hydrogen sulfate ion acts as an acid in the reaction HSO₄⁻ + H₂O ⇌ SO₄²⁻ + H₃O⁻, where it donates a proton to water, forming a hydronium ion and a sulfate ion.

Step-by-step explanation:

The hydrogen sulfate ion (HSO₄⁻) can act as an acid or a base. When it acts as an acid, it donates a proton (H⁺) in a reaction. The correct equation where HSO₄⁻ acts as an acid is:

HSO₄⁻ + H₂O ⇌ SO₄²⁻ + H₃O⁻ (Option d)

In this reaction, the hydrogen sulfate ion donates a proton to the water molecule (∗OH⁺), forming a hydronium ion (H₃O⁻) and creating the sulfate ion (SO₄²⁻). Therefore, HSO₄⁻ is demonstrating its acidic behavior by being a proton donor in accordance with the Brønsted-Lowry acid-base theory.