In the redox reaction between Cr ₂ O ₇²⁻ / H ⁺ and sulphite ion, what is the number of moles of electrons involved in producing 3.0 moles of the oxidised product?

Step-by-step solution

The balanced redox reaction between dichromate ion and sulphite ion in acidic medium is given by: Cr ₂ O ₇²⁻ + 3 SO ₃²⁻ + 8 H ⁺ 2 Cr ³⁺ + 3 SO ₄²⁻ + 4 H ₂ O The oxidation half-reaction is the oxidation of sulphite ion to sulphate ion: SO ₃²⁻ + H ₂ O SO ₄²⁻ + 2 H ⁺ + 2e⁻ In this half-reaction, 2 moles of electrons are involved in the production of 1 mole of the oxidised product, which is SO ₄²⁻ . For the production of 3.0 moles of the oxidised product ( SO ₄²⁻ ), the number of moles of electrons involved is: 3.0 mol