Aldehydes undergo oxidation using potassium dichromate to form carboxylic acids. Ketones are more stable than aldehydes because carbonyl groups are attached on both sides. When potassium dichromate is used, its orange color changes to green due to aldehydes being oxidized to carboxylic acids. Ketones do not cause a color change. The overall reaction shows aldehydes being oxidized to carboxylic acids using dichromate ion.

1. unds will undergo oxidation usina pasum 25) Which of the following compounds will un
dichromate to form a carboxylic acid? B. a A and B only b. A and C only B only d C only
Solution
Aldehydes are unstable and easily undergo oxidation reaction. Ketones are stable due to +I
groups are attached both sides of the carbonyl.
Potassium Dichromate colour is in orange and changes to green (Aldehydes to carboxylic
acid).
Ketones ( No colour change)
Overall reaction can be written as
3 RCHO + Cr 2 O 7 - 2 +8H + ......> 3 RCOOH + 2 Cr +3 + 4H 2 O
Answer is C. B only