Question

The reagent that can be used to distinguish between methanoic acid and ethanoic acid is:

• A. ammoniacal silver nitrate solution
• B. neutral ferric chloride solution
• C. sodium hydroxide solution
• D. sodium carbonate solution

Answer 1

Answer: (A)

ammoniacal silver nitrate solution

Answer 2

Formic acid (methanoic acid) can reduce ammoniacal silver nitrate (Tollens reagent) to silver mirror because it acts as reducing agent and in it H-atom linked with $-COOH$ group is easily oxidized to $-OH$ group, as follows: $HCOOH+A{{g}_{2}}O\xrightarrow[{}]{amm.\,AgN{{O}_{3}}}{{H}_{2}}O$ $+C{{O}_{2}}+\underset{\begin{smallmatrix} silver \\\ mirror \end{smallmatrix}}{\mathop{2Ag\downarrow }}\,$ While acetic acid (ethanoic acid) cannot react with ammoniacal silver nitrate solution.