Use bond-counting (O > C > H; C-C bonds count zero). When ethanal, CH3CHO, is oxidised to ethanoic acid, CH3COOH, the change in oxidation number of the functional (non-methyl) carbon atom is

JEE Advanced levelSingle correct optionDifficulty 3 of 3rx039

Use bond-counting (O > C > H; C-C bonds count zero). When ethanal, $CH X_{3} CHO$ , is oxidised to ethanoic acid, $CH X_{3} COOH$ , the change in oxidation number of the functional (non-methyl) carbon atom is

In ethanal, the carbonyl carbon has one C-H (

- 1

) and C=O (

+ 2

+ 1

. In ethanoic acid it has C=O (

+ 2

) and C-OH (

+ 1

+ 3

. The change is

+ 3 - (+ 1) = + 2

. The methyl carbon stays at

- 3