General Chemistry

Question

From the reaction, which is the substance undergoing oxidation?

Fe + H2SO4 → FeSO4 + H2

Answer 1

Fe + H₂SO₄ ----> FeSO₄ + H₂

Fe is oxidize, because Fe lost 2 e^- from iron (Fe) to iron ion (Fe²⁺)

Answer 2

Fe (s) + H₂SO₄ (aq) → FeSO₄ (aq) + H₂ (g)

Write out the net ionic equation by letting aqueous species dissociate and cancel out identical compounds on each side of the reaction arrow (spectator ions).

Fe(s) + 2H⁺ (aq) + SO₄^-2 (aq) → Fe⁺² (aq) + SO₄^2- (aq) + H₂ (g)

Fe(s) + 2H⁺ (aq) → Fe⁺² (aq) + H₂ (g) Net ionic equation

This is a red-ox reaction. Follow each element from the net ionic equation.

Fe(s) → Fe⁺² (aq)

2H⁺ (aq) → H₂ (g)

These two equations above are wrong. That reaction arrow is like an equals sign, and the two reactions above are not balanced for charge. so you need to balance the charge in each by adding electrons. Electrons are negative in charge so they must go on the side where the positive charged species appear in order to maintain electrical neutrality.

Fe(s) → Fe⁺² (aq) + 2e^-

2H⁺ (aq) +2e^- → H₂ (g)

OIL RIG (Oxidation Is Loss, Reduction is Gain) for electrons.

So, Fe(s) → Fe⁺² (aq) + 2e^- Oxidation since this shows a process of Fe losing two electrons.

and 2H⁺ (aq) +2e^- → H₂ (g) Reduction since this shows a process of 2H⁺ gaining two electrons.