Question

How Formic acid and formaldehyde can be distinguished?

Answer 1

Formic acid

1. Formic acid have formula $\mathrm{HCOOH}$
2. It is the simplest carboxylic acid
3. Formic acid are acidic in nature
4. They are liquid at room temperature due to hydrogen bonding.

Formaldehyde

1. Formaldehyde have molecular formula $\mathrm{HCHO}$.
2. They are simplest form of aldehyde
3. They are colourless gases because of the absence of hydrogen bonding.

Distinguishing Formic acid and Formaldehyde

• Formic acid on reaction with sodium bicarbonate releases carbon dioxide gas, on the other hand formaldehyde does not react with sodium bicarbonate.
• Reaction with formic acid

$\underset{\mathrm{Sosium}\mathrm{bicarbonate}}{{\mathrm{NaHCO}}_3}+\underset{\mathrm{Formic}\mathrm{acid}}{\mathrm{HCOOH}}\to \underset{\mathrm{Sodium}\mathrm{formate}}{\mathrm{HCOONa}}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}}$

• The carboxylate group present in the formic acid reacts with sodium bicarbonate, ${\mathrm{NaHCO}}_3$ to produce ${\mathrm{CO}}_2$ (released from the bicarbonate ion), a salt, and water.
• The salt formed in the reaction is sodium formate, which is the sodium salt of formic acid.

Hence, sodium bicarbonate can be used to distinguish between formic acid and formaldehyde.