Question

In Tollens test, aldehydes

• A. are oxidised to acids
• B. are reduced to alcohol
• C. neither reduced nor oxidised
• D. precipitate $Ag^+$ as $AgCl$

Answer 1

Answer: (A)

are oxidised to acids

Answer 2

When an aldehyde is heated with Tollens reagent, it oxidised to acids and latter is reduced to metallic silver, which deposits on the wall of test tube as bright silver mirror.
$R C H O+\underbrace{2\left[A g\left(N H_{3}\right)_{2}\right]^{+}+3 O H^{-}}_{\text {Tollens reagent }} {->[\text{Heat}]}$
$\underset{\text { carboxylate ion }}{ RCOO _{2}^{-}}+\underset{\text { silver mirror }}{2 Ag }+4 NH _{3}+2 H _{2} O$