Examples of redox reactions

1. The breathalyzer reaction:
2K₂Cr₂O₇(aq) + 3CH₃CH₂OH(aq) + 8H₂SO₄(aq) -----> 2Cr₂(SO₄)₃(aq) + 3CH₃COOH(aq) + 2K₂SO₄(aq) + 11H₂O(l)

(a) Write the net ionic equation for this reaction.
(b) Which compound is the oxidizing agent?
(c) Which compound is oxidized?

2. Water "filters" that remove chlorine:
2Cl₂(aq) + C(s) + 2H₂O(l) -----> CO₂(aq) + 4HCl(aq)

(a) Which species is the reducing agent?
(b) Which species is reduced?

3. Hydrogen peroxide is an important redox reagent. It is used as an antiseptic to kill bacteria and also as a bleaching agent for "perming" human hair. Hydrogen peroxide can act as both a reducing agent and an oxidizing agent in acidic solution.
(a) Write the balanced half reaction equation for hydrogen peroxide acting as an oxidizing agent in an acidic solution.
(b) Write the balanced half reaction equation for hydrogen peroxide acting as a reducing agent in an acidic solution.
(c) Write a balanced equation for the reaction in which hydrogen peroxide oxidizes and reduces itself, i.e., disproportionates.