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What is Formic Acid?

Before understanding anything about formic acid let us understand what is an acid. An acid is any chemical compound that releases a considerable amount of H+ ions in an aqueous solution. To test the acidic or basic nature of any compound you can either use an acid-base indicator or litmus paper. Now coming to formic Acid, formic Acid belongs to the carboxylic acid group. It is the first member of the carboxylic acid group and is written as HCOOH, also called methanoic acid. As we see in the formula, the acid contains a single carbon atom, 2 oxygen atoms, and 2 hydrogen atoms. 


Formic Acid Structure

The structure of formic Acid is simple since it is the first carboxylic Acid of the series and it contains a single carbon atom, which gives it the name of methanoic acid. The structure involves a carbon atom having a single bond with hydrogen, a double bond with oxygen, and another single bond with oxygen which is in turn bonded with a hydrogen atom. You can notice the same in the image below, it represents formic Acid structure HCOOH.

(Image to be added soon)


Physical Properties of HCOOH

  • The IUPAC name of Formic acid is Methanoic acid, as we've seen earlier. It is the first member of the homologous series of carboxylic acids. So we've now seen the structure and IUPAC name of Formic acid. 

  • Formic acid in appearance is like a thick transparent liquid and by its looks, it is impossible to identify it. 

  • The melting point of formic acid is not very high. Formic acid melting point is merely 8.4°C. 

  • The boiling point of Formic acid is a little over that of water. The boiling point of formic acid is 100.8°C. 

  • Formic acid isn't a very dense liquid and has a low density of 1.22g/cm³. 

  • Since formic acid is the first member of the homologous series, the molecular weight of the acid isn't very high as well. The molecular weight of Methanoic acid is 46.03 g/mol.

  • Formic acid has a characteristic pungent and irritating odour.

  • It is soluble and miscible with water. 


Chemical Properties of Formic Acid 

  • Formic acid as the name suggests is acidic and is capable of turning blue litmus into red litmus.

  • Formic acid is a Hydrogen bond donor 

  • Formic acid contains carbon and carbon forms of covalent bonds in most cases. In formic acid as well, carbon forms all covalent bonds. Formic acid contains only covalent bonds. 

  • Formic acid is capable of reducing mercuric chloride into mercurous chloride which results in a white precipitate. The equation to the reaction is given below 

HCOOH + 2HgCl2 → Hg2Cl2 + 2HCl + CO2

  • Formic acid also reacts with phosphoric pentachloride and results in forming formyl chloride, phosphoryl chloride, and hydrogen chloride. Given below is the reaction to the equation. 

HCOOH + PCl5 → HCOCl + POCl3 + HCl


Methods of Manufacturing Formic Acid

By reacting methyl formate with formamide

Upon the reaction of methanol and carbon monoxide in the presence of a strong base, methyl formate is formed. The chemical reaction to the above-mentioned method is given below 

CH3OH + CO → HCO2CH3

The method is also used in industries, the reaction is performed under special conditions. Typical  conditions for the feasible progress of the reaction are 

  • 80 °C temperature

  • 40 atm pressure 

  • liquid phase

The most commonly used base in this process is sodium methoxide. 

Hydrolysis of the obtained methyl formate gives our desired compound as the main product. Along with this we also get certain byproducts. The reaction of the hydrolysis goes as follows 

HCO2CH3 + NH3 → HC(O)NH2 + CH3OH

2 HC(O)NH2 + 2H2O + H2SO4 → 2HCO2H + (NH4)2SO4 

However, the above-mentioned procedure has a disadvantage. We need to dispose of the ammonium sulfate which is a by-product of the reaction. Disposing of this is a tedious process as the chemical is hazardous and can do great harm to the environment. This has caused many manufacturers problems since several governments have banned the disposal of chemicals into the environment to protect it. 

FAQ (Frequently Asked Questions)

1. Where is formic acid obtained in nature?

This is a fun fact about formic acid! Ants are natural producers of formic acid. Formic acid is obtained in high concentrations in the venom produced by ants. The name formic acid itself comes from "Formica" which is the Latin word for ants. Ant bites do contain a large amount of formic acid, they've certain inbuilt chemicals that facilitate the production of formic acid naturally. Hence, whenever you get an ant bite next time, before applying anything else apply a basic substance. It will reduce the pain considerably and provide quick relief by neutralizing the acid in the ant bite. 

2. What are the uses of formic acid?

  • Formic acid and citric acid or HCL is used as a mixture. Together, they are strong enough to remove iron oxide deposits.

  •  Formic acid is also used in the production of important industrial chemicals

  • It is used as a reducing agent. It can reduce both sodium and potassium dichromate.

  • It is a highly useful material in the tanning and dyeing industries. 

  • Owing to its antibacterial properties Formic acid is also very highly used in the agriculture industry. It is known to act as a pesticide and has proven beneficial to prevent crops from being attacked by different kinds of pests. 

3. What is the Lewis structure of formic acid?

Lewis structure is a structure of a compound which pictorially represents all the bonds and even the lone pairs. It gives the viewers a clear picture of the compound. The Lewis structure of formic acid has 5 bond pairs and 4 lone pairs. The octet rule is satisfied in all the atoms of formic acid and hence the acid is chemically stable. The structure has 2 lone pairs on each oxygen respectively. Given below is the Lewis structure of the acid, it shall give you a better idea! 

(Image to be added soon)

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