Answer to Question #260253 in Inorganic Chemistry for shamsa

Question

2. Oxidation-Reduction reactions

1. Iron (II) is oxidised to iron (III) by chlorine. Use the half reaction method to balance the equation for the reaction: Fe2+ + Cl2 → Fe3+ + Cl- 2. The dichromate ion oxidizes iron (II) to iron (III) in acid solution. Balance the equation:

Cr2O 2-

+ H3O+

+ Fe2+

→ Cr3+

+ Fe3+

+ H2O, by the half-reaction method

Answer 1

Cr2O72-→ Cr3+

Fe2+ → Fe3+

Cr2O72-→ 2Cr3+

We need a coefficient 2 on the product side because Cr2O72- has an extra chromium

Fe2+ → Fe3+

Cr2O72-+ 14H+ → 2Cr3+ + 7H2O

Cr2O72-+ 14H+ + 6e- → 2Cr3+ + 7H2O

Cr2O72-+ 14H+ + 6e- → 2Cr3+ + 7H2O

This one has more, so just leave it the same

6 (Fe2+ → Fe3+ + e-) → 6Fe2+ → 6Fe3+ + 6e-

6Fe2+ Cr2O72-+ 14H+ + 6e- → 2Cr3+ + 7H2O + 6Fe3+ + 6e-

6Fe2+ Cr2O72-+ 14H+ → 2Cr3+ + 7H2O + 6Fe3+