Question

When acetaldehyde is heated with Fehling's solution, a red precipitate is formed. The red precipitate is due to the formation of :

• A. $C{u}_{2}O$
• B. $Cu$
• C. $CuO$
• D. $CuS{O}_4$

Answer 1

The correct option is A $C{u}_{2}O$

Fehling's solution is tartaric acid complex of cupric ions. It is blue in color. 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.
The reaction is as follows:
$C{H}_{3}CHO+2C{u}^{+}+5O{H}^{-}\to C{H}_{3}C{O}^{-}+C{u}_{2}O+3H_{2}O$
Red ppt.