Exercise 9 | Oxidation-Reduction Reactions

Balance the following redox reactions:


1) I2 (s) + OCl- (aq) → IO3- (aq) + Cl- (aq) under acidic conditions

2) Cr2O72- (aq) + H2S (g) → Cr3+ (aq) + S (s) under basic conditions

3) Cu (s) + SO42- (aq) → Cu2+ (aq) + SO2 (g) under basic conditions

1) I2 (s) + 6 H2O (l) → 2 IO3- (aq) + 12 H+ (aq) + 10 e-

OCl- (aq) + 2 H+ (aq) + 2 e- → Cl- (aq) + H2O (l)

Balanced equation: I2 (s) + 5 OCl- (aq) + H2O (l) → 2 IO3- (aq) + 5 Cl- + 2 H+ (aq)

 

2) Cr2O72- (aq) + 7 H2O + 6 e- → 2 Cr3+ (aq) + 14 HO- (aq)

H2S (g) + 2 HO- (aq) → S (s) + 2 H2O (l) + 2 e-

Balanced equation: Cr2O72- (aq) + 3 H2S (g) + H2O (l) → 2 Cr3+ (aq) + 3 S (s) + 8 HO- (aq)

 

3) Cu (s) → Cu2+ (aq) + 2 e-

SO42- (aq) + 2 H2O (l) + 2 e- → SO2 (g) + 4 HO- (aq)

Balanced equation: Cu (s) + SO42- (aq) + 2 H2O (l) → Cu2+ (aq) + SO2 (g) + 4 HO- (aq)