Have you ever used vinegar at home? That sour smell and taste mostly comes from a chemical called ethanoic acid. It’s a common acid used in kitchens, labs, and industries. You might not realize it, but this acid is all around us in foods, cleaning products, and even in making other chemicals. In this article, we’ll explore what ethanoic acid is, how it looks and behaves, where it’s used, and some important reactions it takes part in. Lets scroll down to know more about ethanoic acid.

What is Ethanoic Acid?

Ethanoic acid is an organic compound with a carboxyl group belonging to the carboxylic acid functional group. The chemical formula of ethanoic acid is written as \(\text{CH}_3COOH\), or it can be represented as \(C_2H_4O_2\)too.

After the formic acid, the ethanoic acid structure contains a methyl group (\(CH_3\)) attached to the carboxyl functional group (COOH). As you may know, the carboxyl group has a double bond between carbon and oxygen atom, and a hydroxyl (OH) is attached to the central carbon atom. Since the structural formula of ethanoic acid is (\(\text{CH}_3COOH\)), its structure can be represented as

Electron Dot Structure of Ethanoic Acid

Ethanoic acid electron dot structure can be represented as

Here are some essential things that can be inferred from the ethanoic acid structure:

• The alpha carbon of the methyl group in the ethanoic acid is \(sp^2\) hybridized.

• From the electron dot structure of ethanoic acid, it is clear that it has one hydrogen bond donor and two hydrogen bond acceptor atoms through electronic configuration. Thus, there is a hydrogen bond formation between the acetic acid molecule when the electronegative cloud of the oxygen atoms of one molecule attracts the less electronegative hydrogen electron cloud of the other acetic acid molecule.

• Ethanoic acid exists as a dimer in its liquid and vapour phase because of the intermolecular hydrogen bonding between the two molecules of ethanoic acid.

• The dimer of ethanoic acid in the vapour phase exists at 120°C temperature.

Ethanoic acid Chemical Reaction

Since the pH of ethanoic acid is 3, it is regarded as a weak acid because when dissolved in water, it partially dissociates into constituent ions.

However, it reacts differently with a variety of compounds:

• Reaction with Base

It forms one molecule of salt and one molecule of water when ethanoic acid reacts with a base.

Ethanoic acid reacts with sodium hydroxide to form sodium ethanoate salt and water as by-products. The salt produced from the reaction has a variety of applications, like

1. Used for sulfuric acid neutralization in the textile industry to clean the fibre.
2. It is used as a preservative and mild seasoning and flavouring agent in the food industry,
3. It is used as a buffering agent along with ethanoic acid to keep the pH of the medium constant.
4. It is used to produce methane gas by reacting it with soda lime.

• Reaction with Carbonates and Hydrogen Carbonates

When ethanoic acid reacts with carbonates and bicarbonates, it leads to the formation of salt formation, carbon dioxide, and water.

• Reaction with Metals

The reaction of ethanoic acid with metals like sodium, and magnesium, lead to hydrogen gas evolution along with salt formation.

\(CH_3COOH\ +\ 2Na\ \longrightarrow \ 2CH_3COONa\ +\ H_2\)

• Reaction with Ammonia

When acetic acid reacts with ammonia, it leads to ammonium salt production, and when ammonium salt is heated at a high temperature leads to ethanamide formation.

• Reaction with Ethanol (Esterification Reaction)

When ethanoic acid reacts with Ethanol, it leads to a new class of organic compounds formation, known as esters.

The reaction of ethanol and ethanoic acid is described as

Esters have a fruity and sweet aroma that can be used in perfumes and synthetic flavouring agents manufacturing.

When esters react with alkalis, it leads to the formation of carboxylic acid salt and alcohol. The carboxylic acid salt formed as a by-product is the soap that is in our daily lives, and this reaction is known as the saponification reaction.

Learn about esterification here.

Properties of Ethanoic Acid

• Ethanoic acid is sour to taste and has a pungent odour that makes it perfect to use as a preservative.
• The molecular weight or molar mass of ethanoic acid is 60.025g/mol.
•  It is slightly heavier than water as it has a density of \(1.05g/cm^3\).
• The boiling and melting point of ethanoic acid is 118°C and 16°C, and no wonder it freezes quickly and is referred to as glacial acetic acid.
• Since it is a weak acid, the pH of ethanoic acid is 3.
• Acetic acid is highly soluble in water in all proportions and organic solvents like carbon tetrachloride (CCl4) and carbon disulfide. However, it is miscible when mixed with Ethanol, benzene, acetone, ethyl ether, and glycerol.
• The ethanoic acid dissociation constant (pKa) at 25°C is 4.76.

Important Reactions of Ethanoic Acid

Ethanoic acid takes part in some useful reactions. Let’s look at a few important ones in the table below.

Difference between Ethanol and Ethanoic Acid

Ethanol and ethanoic have similar names, but they are not the same. Check the table to know the difference between ethanol and ethanoic acid.

Uses of Ethanoic acid

The uses of acetic acid in the different industries are as follows:

• The formation of metal ethanoate when ethanoic acid reacts with any metal in the printing industry.
• Acetates are used in the production of photographic films.
• In the textile industry, acetates help to manufacture synthetic fibres. Rayon fibre is created with the help of ethanoic acid.
• Esters from the reaction of ethanoic acid and Ethanol can be used as solvents to produce paints and resins. It is used to produce vinyl acetate monomers that are used in the production of adhesive, glue, sealants, and binders.
• Ethanoic acid is used in large quantities in the rubber industry.
• It is also used in the production of camphor and cooling ingredients.
• Vinegar is useful in reducing high blood sugar concentration, and ethanoic acid is used in blood cell examination to lyse the blood cells.

Ethanoic acid is a vital topic to understand while studying organic chemistry. In order to follow up more such basic information, quickly install the Testbook App from the Google Play Store.