Formic Acid (HCOOH)

Last Updated : 23 Jul, 2025

Formic Acid is one of the basic organic acids belonging to the family of Carboxylic Acid. Its chemical name is Methanoic Acid.

In this article, we will learn about Formic acid in detail, including its formula, structure, and properties.

What is Formic Acid?

Formic Acid also called Methanoic Acid is a natural acid that is found in ant stings. Its molecular formula is HCOOH. As it has one carbon atom and belongs to the Carboxylic Acid family, its IUPAC name is Methanoic acid.

Its first artificial synthesis was done by French chemist Joseph Gay-Lussac.

Formic Acid Formula

The molecular or chemical formula of Formic acid is :

HCOOH or HCO2H or CH2O2

We have one carbon atom two hydrogen atoms, and two oxygen atoms in its structure. The molecular weight of formic acid is 46.03 g/mol. A Hydrogen atom bonded to a carboxylic acid. Small hydrogen atoms do not much interfere with O-C-O bond angles in the functional carboxylic acid group. The coming Hydrogen atom forms a bond with hydroxyl Oxygen H-C-O-O.

Formic Acid Structure

The Molecular Structure of Formic Acid has one Carbon atom, two oxygen atoms and two hydrogen atoms. Here, one carbon atom is attached to one oxygen atom by the double covalent bond and one single covalent bond with a hydroxide ion and one covalent with a hydrogen atom. 

The molecular structure of Formic acid is shown in the image added below:

Formic Acid Structure

Formic Acid Preparation

Formic Acid is prepared by various processes. Some of the processes of Preparation of Formic Acid are :

  • Formic acid is prepared by the reaction of formamide with sulfuric acid.

2HCONH2 + 2H2O + H2SO4 → 2HCO2H + (NH4)2SO4

  • Formic acid is also produced as a by-product of the manufacturing of acetic acid (also called ethanoic acid).
  • Another method for the production of Formic acid is by combining methanol with carbon mono oxide in the presence of a strong base which gives acetic acid which on hydrolysis gives formic acid.

CH3OH + CO → HCOOCH3

HCO2CH3 + H2O → HCO2H + CH3OH

Physical Properties of Formic Acid

Formic Acid has the following physical properties:

  • Formic Acid has a density of 1.22 g/cm3.
  • Boiling Point of Formic Acid is 100.8˚C.
  • Melting Point of Formic Acid is 8.4°.
  • Formic acid is a colourless liquid.
  • Molecular weight of Formic Acid is 46.03 g/mol.
  • Formic acid is miscible with water.
  • Formic acid has a pungent odor.

Chemical Properties of Formic Acid

The chemical properties of Formic Acid are :

  • Formic Acid has a pH 0f 3.25.
  • Formic Acid has dissociation constant(pKa) of 3.75.
  • Formic Acid acts as reducing agent.
  • It doesn't form Anhydride.
  • It has some characters of Aldehyde.

Formic Acid reacts with a variety of substances to form various products. The common chemical reactions of formic acid are :

  • Formic Acid reacts with Phosphoric Pentachloride forming Phosphoryl Chloride, hydrogen chloride, and formyl chloride.

HCOOH + PCl5 → HCOCl + POCl3 + HCl

  • Formic Acid can form Mercurous Chloride from Mercuric Chloride forming a white precipitate.

HCOOH + 2HgCl2 → Hg2Cl2 + 2HCl + CO2

Uses of Formic Acid

Some uses of formic acid are :

  • It is used for livestock feed. When sprayed on the hay and other livestock slows their decay process and hence it is widely used for livestock feeding.
  • It is used in the production of leather, textile, and rubber.
  • It is useful as a preservative and artificial flavouring.
  • It is a chief ingredient in fuel cells.
  • It acts as an antimicrobial agent.
  • It acts as a reducing agent to reduce potassium and sodium dichromate.

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