Question

1. Iodic acid, HIO3, can be prepared by reacting iodine, I2, with concentrated nitric acid. The skeleton equation is: I2(s) + NO3 - (aq) → IO3 - (aq) + NO2(g). Balance this equation using the half reaction method.

Answer 1

Solution:

Unbalanced chemical equation: I₂(s) + NO₃⁻(aq) → IO₃⁻(aq) + NO₂(g)

Oxidation half-reaction:

I₂⁰ + 6H₂O − 10e⁻ → 2IO₃⁻ + 12H⁺

Reduction half-reaction:

NO₃⁻ + 2H⁺ + e⁻ → NO₂ + H₂O

Net reaction:

I₂⁰ + 10NO₃⁻ + 8H⁺ → 2IO₃⁻ + 10NO₂ + 4H₂O

Balanced chemical equation: I₂(s) + 10NO₃⁻(aq) + 8H⁺(aq) → 2IO₃⁻(aq) + 10NO₂(g) + 4H₂O(l)

I₂(s) acts as reducing agent

NO₃⁻(aq) acts as oxidizing agent