Question

Sodium bisulfite is an ionic compound that is used as a mild bleaching agent and a food preservative. It contains the bisulfate ion, an amphiprotic ion with the chemical formula HSO₃-.

a. Write the chemical equation for the reaction of HSO₃- with OH-. Is the bisulfite ion functioning as an acid or a base in this reaction?
b. Write the chemical equation for the reaction of HSO₃- with H₃O+. Is the bisulfite ion functioning as an acid or a base in this reaction?

Answer 1

a)

HSO₃⁻ + OH⁻ → H₂SO₄⁽²⁻⁾

In this reaction, we know that OH will act as a base. which means that the bisulfite ion will act as an acid

also because SO₃⁽²⁻⁾ will be relative more stable than O⁽²⁻⁾ because of larger valence shell. so HSO₃ will protonate. making it the acid

b)

HSO₃⁻ + H₃O⁺ → H₂SO₃

Here, the hydronium ion will be the one to protonate because that will help it form water, which is a much stabler compound

so the hydronium ion will protonate, making it the acid and the bisulfite will take that proton, making it the base