Question

When acetaldehyde is heated with Fehling's solution, it gives a red precipitate of :

• A. $Cu$
• B. $CuO$
• C. $C{u}_{2}O$
• D. $Cu+C{u}_{2}O+CuO$

Answer 1

Answer: (C)

$C{u}_{2}O$

Fehling's solution is a tartaric acid complex of cupric ions. It is blue in colour. When it is heated with acetaldehyde, a red precipitate of cuprous oxide $\left(C{u}_{2}O\right)$ is obtained. In this reaction, acetaldehyde reduces cupric ions to cuprous ions.

$C{H}_{3}CHO+2C{u}^{2+}+5O{H}^{-}\to C{H}_{3}CO{O}^{-}+C{u}_{2}O\downarrow +3H_{2}O$

Option C is correct.