Ethanoic Acid

Last Updated : 8 Apr, 2026

Ethanoic acid is an organic compound that belongs to the carboxylic acids and contains the functional group (–COOH), which gives it acidic properties. It is also known as acetic acid and is a colourless liquid with a strong smell and a sour taste. In dilute aqueous form, it is known as vinegar and is widely used in food preservation. Ethanoic acid is also important in chemical industries and laboratories due to its versatile properties.

Structure of Ethanoic Acid

  • Ethanoic Acid Structural Formula is CH3COOH, which may alternatively be written as CH3CO2H or C2H4O2 in its condensed form.
  • It has a molecular mass of 60.05 g/mol (or molar mass).
  • The structure of ethanoic acid consists of two carbon atoms, four hydrogen atoms, and two oxygen atoms.
  • In this compound, one carbon atom is attached to three hydrogen atoms, forming a methyl group (CH₃–), while the second carbon atom is attached to two oxygen atoms.
  • One of these oxygen atoms is connected to the carbon atom by a double bond (C=O), forming a carbonyl group, and the other oxygen atom is attached by a single bond along with a hydrogen atom (–OH), forming a hydroxyl group.
  • These two groups together make the carboxyl functional group (–COOH), which is responsible for the acidic nature of ethanoic acid.

Structure of Ethanoic Acid

Physical Properties

Ethanoic acid shows several physical properties that help in identifying and understanding this compound. These properties are related to its appearance, smell, solubility, and physical state. It is as follows:

  • Ethanoic acid is a colourless liquid with a strong and pungent smell.
  • It has a sour taste, which is responsible for the characteristic taste of vinegar.
  • Another important property is that ethanoic acid is completely soluble in water.
  • It mixes easily with water in all proportions because its molecules can form hydrogen bonds with water molecules.
  • Ethanoic acid also has a relatively high boiling point (about 118°C) compared to many other organic compounds with similar molecular mass.
  • This happens because of strong intermolecular hydrogen bonding between its molecules.
  • A unique property of pure ethanoic acid is that it freezes at about 16.6°C, forming ice like crystals.
  • Because of this property, pure ethanoic acid is known as glacial acetic acid.
  • Thus, the colorless nature, strong smell, sour taste, high boiling point, and complete solubility in water are some important physical properties of ethanoic acid.

Chemical Properties(Reactions)

Ethanoic acid is a weak organic acid that belongs to the carboxylic acid group (−COOH). Because of this acidic functional group, it undergoes several chemical reactions similar to other acids. These reactions show its acidic nature and ability to react with different substances.

Various types of reactions are:

1) Reaction with Metals

  • Like other acids, ethanoic acid reacts with active metals such as sodium, potassium, or magnesium to form salt and hydrogen gas.

2CH_3COOH + 2Na \rightarrow 2CH_3COONa + H_2

  • Ethanoic acid reacts with sodium metal to form sodium ethanoate and hydrogen gas.
  • The hydrogen gas is released as bubbles.

Example:
When a small piece of sodium is added to ethanoic acid, bubbles of hydrogen gas are produced.

2) Reaction with Bases (Neutralization Reaction)

CH_3COOH + NaOH \rightarrow CH_3COONa + H_2O

  • Ethanoic acid reacts with sodium hydroxide to produce sodium ethanoate and water.

Example:
When ethanoic acid reacts with sodium hydroxide solution, the acidic nature of the acid is neutralized.

3) Reaction with Carbonates and Bicarbonates

  • Ethanoic acid reacts with carbonates or bicarbonates to produce salt, water, and carbon dioxide gas.

2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + H_2O + CO_2

  • Ethanoic acid reacts with sodium carbonate to form sodium ethanoate, water, and carbon dioxide gas.
  • The carbon dioxide gas causes effervescence (bubbling).

Example:
When ethanoic acid reacts with baking soda (sodium bicarbonate), bubbles of carbon dioxide are produced.

4) Esterification

  • Ethanoic acid reacts with alcohol in the presence of concentrated sulfuric acid to form ester and water.
  • This reaction is called esterification.

CH_3COOH + C_2H_5OH \xrightarrow{conc.\ H_2SO_4} CH_3COOC_2H_5 + H_2O

  • Ethanoic acid reacts with ethanol to form ethyl ethanoate, which has a pleasant fruity smell.

Example:
This reaction is used in the production of perfumes and flavoring agents.

Method of Preparation of Ethanoic Acid

Ethanoic acid can be prepared by different chemical and natural methods. The most common methods involve the oxidation of alcohols or aldehydes and the fermentation of ethanol. Some important methods are explained below:

1) Oxidation of Ethanol

  • Ethanoic acid can be prepared by the oxidation of ethanol (ethyl alcohol) using strong oxidizing agents such as acidified potassium dichromate or alkaline potassium permanganate.
  • During oxidation, ethanol is first converted into ethanal and then further oxidized to form ethanoic acid.

CH_3CH_2OH + 2[O] \rightarrow CH_3COOH + H_2O

  • In this reaction, ethanol reacts with oxygen supplied by the oxidizing agent.
  • The alcohol group (−OH) is oxidized and converted into a carboxylic acid group (−COOH), forming ethanoic acid.

2) Oxidation of Ethanal

  • Ethanoic acid can also be prepared by the oxidation of ethanal (acetaldehyde) using oxidizing agents like potassium permanganate or potassium dichromate.

CH_3CHO + [O] \rightarrow CH_3COOH

  • Here, ethanal gains oxygen during oxidation and is converted into ethanoic acid.

3) Fermentation of Ethanol (Biological Method)

  • Ethanoic acid can also be produced by the fermentation of ethanol in the presence of bacteria such as Acetobacter.
  • This process occurs when alcohol is exposed to air for a long time, converting it into vinegar.

C_2H_5OH + O_2 \rightarrow CH_3COOH + H_2O

  • In this process, bacteria oxidize ethanol using oxygen from the air to produce ethanoic acid.

Uses of Ethanoic Acid

Ethanoic Acid found its importance in variety of things some of the common uses of Ethanoic Acid are:

  • It is used as a solvent in a variety of chemical processes.
  • Vinegar, esters, and synthetic polymers are all made from it.
  • It is used in labs as a lysing agent for blood cells.
  • It is used to treat fungal infections.
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