Formic Acid (HCOOH)

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 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.

Read More,

• Acids, Bases and Salts
• Carboxylic Acids
• Chloroacetic Acid
• Trichloroacetic Acid
• Strong and Weak Acids

FAQs on Formic Acid

Is Formic Acid a Natural Acid?

It exists naturally in various ways like a bee, ant stings venom and it is a valuable synthetic organic reagent. It is very effective at low concentrations. Since it is an antibacterial material, humans use formic acid as a food preservative, antimicrobial agent, and artificial flavoring.

What is the Formula of Formic Acid?

The structural formula of Formic acid is HCOOH.

What is the IUPAC Name of Formic Acid?

The IUPAC name of Formic Acid is Methanoic Acid. As, it has only one carbon atom, hence the name ‘meth’

What is the pH of Formic Acid?

The pH of Formic Acid is 3.25

What is the pKa of Formic Acid?

The pKa of Formic Acid in water is 3.75

What is the Molecular Mass of Formic Acid?

The molecular mass of formic acid (HCOOH) is approximately 46.03 atomic mass units (amu).

Is Formic Acid a Strong Acid?

We define a strong acid as an acid which on dissolving in water easily dissociates into cations and anions and easily releases Hydronium ions. Now even though formic acid releases hydronium ions on dissolving in water it is not considered a strong acid as it does not completely dissolve in its aqueous solution. Hence, Formic acid is considered to be a weak acid.

How is Formic Acid Prepared in a Lab?

Formic Acid in a laboratory is prepared by heating glycerol with oxalic acid at 100 to 110 °C. The compound formed after this reaction is Glycerol Mono Oxalate which on further heating at 100 to 110 °C in the presence of oxalic acid forms Formic Acid.

Formic Acid is Stronger than Acetic Acid. Explain.

Formic acid is more acidic in nature than acetic acid because the negative charge on the ion formed in the aqueous solution of formic acid is stabilized by the presence of the oxygen atom in the anion thus increasing its stability, and hence Formic acid is more acidic than Acetic acid. Also the +I effect of CH₃ is more than that of H hencce loss of proton becomes difficult in Acetic Acid as comapred to Formic Acid.

Where is Formic Acid found?

Formic acid is found in Ant and bee stings.

How can we Neutralise Formic Acid?

Formic acid (HCOOH) can be neutralized by reacting it with a base, typically sodium hydroxide (NaOH) or potassium hydroxide (KOH), to form water and a corresponding salt. Here’s the neutralization reaction using sodium hydroxide as an example:

HCOOH + NaOH → H₂O + HCOONa

In this reaction, formic acid reacts with sodium hydroxide to produce water and sodium formate. The resulting solution will have a neutral pH, as the acidic and basic properties have been canceled out by the reaction.

What are the Uses of Formic acid?

Formic acid is mainly used as,

• Preservative in Livestock feeds.
• It is used as a food preservative because of its anti-bacterial actions.
• It is used as an artificial flavouring agent.
•  It is used in the production of leather, textile, and rubber.
• It acts as a reducing agent to reduce potassium and sodium dichromate.

What are Bad Effects of Formic Acid?

Various ill effects of Formic acid are,

• Inhalation of formic acid fumes causes irritation of mucous membranes. 
• Formic acid in contact with the skin can cause burns. 
• Formic acid if swallowed causes stones in the kidney.

Is Formic Acid an Organic Acid?

Yes, Formic acid is an organic acid. It is called organic acid because it is formed by the bond between carbon and hydrogen. It is naturally formed in bee stings and ant stings.