Question

What happens when formic acid is heated with Tollen's reagent?

Answer 1

Formic acid (HCOOH) is not true acid, it contains both aldehydes as well as carboxyl group (−COOH) and it behaves as a reducing agent. Therefore formic acid reduces Tollen's reagent to metallic silver. The reaction can be represented as follows:

\[\ce{\underset{Tollen's reagent}{2AgNO3 + 2NH4OH} -> Ag2O + 2NH4NO3 + H2O}\]

\[\ce{Ag2O + \underset{Formic acid}{HCOOH} ->[\Delta] \underset{Silver mirror}{2Ag + CO3} + H2O}\]