AA Redox Chemistry

Reaction: the oxidation of ethanol by the dichromate ion

Reduction: Cr₂O₇^2- + 6e^- → 2Cr³⁺ + 7O^2-

(+6) (-2) (-1) (+3) (-2)

Oxidation: CH₃CH₂OH → CH₃CHO + 2e^- + 2H⁺

3 CH₃CH₂OH → 3CH₃CHO + 6e^- + 6H⁺

Redox: Cr₂O₇^2- + 3CH₃CH₂OH → 2Cr³⁺ + 3CH₃CHO + 3H₂O + 4O^2-

Reaction must be carried out in acid conditions to mop up extra O^2- ions produced

Cr₂O₇^2- + 3CH₃CH₂OH + 8H⁺ → 2Cr³⁺ + 3CH₃CHO + 7H₂O

Reaction: oxidation of nitrate(III) to nitrate(V) by nitrobacter

Overall: NO₂^- _(aq) + ½O_{2 (g)} → NO₃^- _(aq)

(+3) (-2) (0) (+5) (-2)

Oxidation: NO₂^- → NO₃^- _(aq) + 2e^-

(+3) (-2) (+5) (-2)

Reduction: ½O₂ + 2e^-→ O^2-

(0) (-2)