Concept:
This reaction is known as the Wolff–Kishner reduction, where aldehydes or ketones react with hydrazine in a basic medium to form alkanes.
Reaction:
The general reaction for Wolff–Kishner reduction is:
\[
R{-}CHO + NH_2NH_2 \xrightarrow{KOH,\ \Delta} R{-}CH_3 + N_2 + H_2O
\]
Apply to acetaldehyde:
When acetaldehyde (\( CH_3CHO \)) undergoes the Wolff–Kishner reduction with hydrazine and potassium hydroxide, it gives ethane:
\[
CH_3CHO \xrightarrow{NH_2NH_2/KOH} CH_3CH_3
\]
Product:
The product formed is ethane.