Question

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

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

Answer 1

Answer: (D)

$C{u}_{2}O$

Fehlings solution is a tartaric acid complex of cupric ions.
When acetaldehyde is heated with Fehling's solution, it gives a red precipitate of $C{u}_{2}O$
$C{H}_{3}CHO+2C{u}^{2+}+5O{H}^{-}\stackrel{\Delta }{\to }C{H}_{3}CO{O}^{-}+C{u}_{2}O\downarrow +3H_{2}O$
Acetaldehyde is oxidized to acetate ion and cupric ions are reduced to cuprous oxide.