Question

Question #6b532

Answer 1

`4MnO_4^(-)+12H^(+)+5CH_3CH_2OH->4Mn^(2+)+5CH_3COOH+11H_2O`

Explanation:

Potassium permanganate is an oxidant that may be used to oxidise a primary alcohol to a carboxylic acid. The two half-reactions involved in the oxidation of ethanol to ethanoic acid are

`MnO_4^(-)+8H^(+)+5e^(-)->Mn^(2+)+4H_2O" "` (1)

`CH_3CH_2OH+H_2O->CH_3COOH+4H^(+)+4e^(-)" "` (2)

To balance the overall equation, each half-reaction must have the same number of electrons. Multiply (1) by 4 and (2) by 5, to get 20 electrons in each half-reaction.

`4xx` (1):

`4MnO_4^(-)+32H^(+)+20e^(-)->4Mn^(2+)+16H_2O`

`5 xx` (2):

`5CH_3CH_2OH+5H_2O->5CH_3COOH+20H^(+)+20e^(-)`

Next, add the two half-reactions together

`4MnO_4^(-)+32H^(+)+5CH_3CH_2OH+5H_2O+20e^(-)->4Mn^(2+)+16H_2O+5CH_3COOH+20H^(+)+20e^(-)`

Finally, cancel out the like-species on both sides to give

`4MnO_4^(-)+12H^(+)+5CH_3CH_2OH->4Mn^(2+)+5CH_3COOH+11H_2O`