What quantity of electrons is lost when one mole of iron (II) ions is oxidized to iron (III) ?

Analyze the question We need the number of moles of electrons lost when 1 mole of Fe²⁺ is oxidized to Fe³⁺.

Concept Oxidation is loss of electrons (remember OIL RIG: Oxidation Is Loss, Reduction Is Gain). The number of electrons lost per ion equals the change in charge (oxidation state).

Solution The half-equation is:

Fe²⁺ → Fe³⁺ + e⁻

• Oxidation state changes from +2 to +3, which is an increase of 1.
• So each Fe²⁺ ion loses 1 electron.
• 1 mole of Fe²⁺ therefore loses 1 mole of electrons (6.02 × 10²³ electrons).

Checking the options

• A. 0 mole: wrong, because oxidation always involves electron loss.
• B. 3 moles: wrong, because that would be Fe → Fe³⁺ (from the neutral atom).
• C. 1 mole: correct (the option "I mole" is 1 mole).
• D. 2 moles: wrong, because that would be Fe → Fe²⁺.

Tip Count only the change in charge. Fe²⁺ → Fe³⁺ is a change of +1, so 1 electron is lost. Do not count from the neutral atom unless the question starts with Fe.