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Ethanoic acid or Acetic acid belongs to the group of carboxylic acids. It is a two-carbon acid. A solution of 5 to 8% of Ethanoic Acid in water is known as vinegar, which is a common household substance used in Households. Ethanoic Acid tends to freeze in extreme cold and forms a glacier-like appearance. Therefore, sometimes it is also referred to as glacial acetic acid.
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Key Terms: Acetic Acid, acetic glacial acid, sodium ethanoate, ethanoic, acetic acid vinegar, Ethanol
What is Ethanoic Acid?
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Ethanoic acid(CH3COOH) is the most important of the carboxylic acids. Approximately 5 percent by volume solution of Ethanoic acid produced by oxidation and fermentation of natural carbohydrates is called Vinegar. Ethanoic acid is also known as glacial acetic acid because its melting point is 16℃.
Properties of Ethanoic Acid
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The Properties of Ethanoic Acid are discussed below-
| Parameters | Properties |
|---|---|
| Chemical Formula | CH3COOH |
| Density | 1.05 g/cm3 |
| Molar Mass/ Molecular Weight | 60.05g/mol |
| Boiling Point | 118℃ |
| Melting Point | 16℃ |
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Structure of Ethanoic Acid
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Ethanoic Acid has the second simplest structure of carboxylic acid after Methanoic acid. It comprises methyl (–CH3) attached to the carboxylic acid functional group (-COOH)
Structure of Ethanoic Acid
- Ethanoic acid consists of a chain of molecules wherein single molecules are linked to each other through hydrogen bonds. Ethanoic acid in solid state is composed of a number of related molecules.
- 120℃ Is the approximate temperature at which dimers of acetic acid in its vapor phase exist.
- The Dimers of acetic acid can be found in the liquid phase when it is present in a dilute solution. The dimers are majorly affected by solvents that promote the bonding of hydrogen.
Acetic Acid Dimer
- The structure of the acetic acid dimer is CH3(C = O)OH or CH3COOH.
Uses of Ethanoic Acid
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Ethanoic Acid is known to kill bacteria and stop the growth of microorganisms in Pickles, making it the magical ingredient that makes pickles last longer than lemon juice. Ethanoic acid is hydrophilic and easily dissolves in water. The acid has a dielectric constant of 6.2 and can dissolve polar inorganic salts as well as non-polar compounds like oils.
- The most popular use of acetic acid is in the production of vinegar. The food grade vinegar is used in the preparation of food.
Ethanoic Acid/Vinegar used for Pickling
- Ethanoic acid reacts with metals, metal ethanoate, its product, therefore, is used in the printing industry.
- Acetic acid is used in the making of photographic films.
- It is used in the textile industry as synthetic fiber.
- The esters are formed from ethanoic acid and are used in the production of paints and resin.
- Acetyl group derived from acetates in our body is used in the formation of coenzymes which form the core of metabolic processes in the body.
- It is used as an antiseptic due to its antibacterial properties.
- The manufacturer of Rayon Fiber involves the use of acetic acid.
- It treats cancer by injecting directly into the tumor.
- Acetic acid is widely used in manufacturing rubber and various perfumes.
- It is used in the production of Vinyl Acetate Monomer.
Physical Properties of Ethanoic Acid
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The physical properties of Ethanoic Acid, weak acid are-
- Ethanoic Acid is colorless and has a pungent odor.
- Ethanoic acid at room temperature being a lower carboxylic acid is present in the liquid state.
- Ethanoic acid is absolutely soluble in water. The solubility of acids in water decreases with a boom in their molecular weight.
- The freezing point of acetic acid is 290 K; past this temperature, it crystallizes to form glacial acetic acid.
- The boiling factor of ethanoic acid is 391 K.
- The density of ethanoic acid is 1.05 g cm-3 making it denser than water which has a density of 1g cm-3.
- The pH of ethanoic acid is 2.4 at 1 M attention inside the solution.
- In its liquid form, acetic acid is a polar, protic solvent, with a dielectric constant of 6.2. Acetic acid, which is a polar protic solvent, has a dielectric value of 6.2.
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| Difference between acetic acid and glacial acetic acid | Polyurethane foam | Methane |
| Difference between ethanol and methanol | Carbon tetrachloride | Carbonic Acid |
Chemical Properties And Reaction of Ethanoic acids
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Acetic acid is a weak acid that reacts with different compounds to produce useful end-products.
Reaction with a Base-
- When Acetic acid reacts with a base to give salt and water like other mineral acids.
Esterification Reaction-
- When alcohol and carboxylic acid react, an ester is formed which is used to produce paint and resin.
- Ester is a Sweet-smelling ester that can be used in the production of methane gas by reacting with lime soda.
- Ethyl ethanoate is formed with the reaction of ethanoic acid with ethanol. An acidic medium reaction occurs and is known as esterification.
- The formula of esterification is CH3COOH + CH3CH2OH ⥩ CH3COOCH2CH3
Reaction with hydrogen and carbonates-
- When ethanoic acid reacts with carbonates and hydrogen carbonates carbon dioxide, salt and water are produced. Sodium acetate is produced as a salt when reacted with sodium bicarbonate as shown in the reaction below:
2CH3COOH + Na2CO3 –> 2CH3COONa + CO2 + H2O
Things to Remember
- Ethanoic acid or Acetic acid belongs to the group of carboxylic acids.
- Ethanoic acid is a weak acid.
- The chemical formula of Ethanoic acid is CH3COOH.
- Approximately 5 percent by volume solution of Ethanoic acid produced by oxidation and fermentation of natural carbohydrates is called Vinegar.
- The most popular use of acetic acid is in the production of vinegar. The food grade vinegar is used in the preparation of food.
- Ethanoic acid reacts with metals, metal ethanoate, its product, therefore, is used in the printing industry. Acetic acid is widely used in manufacturing rubber and various perfumes.
- Ethanoic acid has antibacterial properties and is used to treat cancer by injecting directly into the tumor.
- Ethanoic acid reacts with base, hydrogen, and carbonates.
- Ethyl ethanoate is made with the reaction of ethanoic acid with ethanol. The Acidic medium reaction occurs and is known as ‘Esterification’.
Sample Questions
Ques. What is Ethanoic acid? (3 marks)
Ans. Acetic acid (CH3COOH), called ethanoic acid, is the most essential of the carboxylic acids. A dilute (about 5 % volume) solution of acetic acid is produced by fermentation and oxidation of herbal carbohydrates is called vinegar; a salt, ester, or acylal of acetic acid is known as acetate. Its main component is vinegar.
Structure of Ethanoic Acid
Ques. What is Ethanoic acid used for? (3 marks)
Ans. Acetic acid is used in the meals industry as vinegar, and as an acidity regulator. Vinegar is famous in Households and helps to keep the bacteria out of food. It is widely used in Pickles.
- It is also a crucial business reagent used within the manufacturing of diverse chemical substances inclusive of polyvinyl acetate, cellulose acetate, metallic acetates, and many others.
- Acetic acid is used to make paints and solvents.
Ques. Is Ethanoic acid used to preserve food? (2 marks)
Ans. Acetic acid is used as vinegar in households. It is utilized as a natural preservative and antibacterial agent within the upkeep of meals, no longer handiest in vegetable pickling but additionally as a lively factor of fit for human consumption movies and in the hurdle maintenance era.
Ques. Why is Ethanoic acid a weak acid? (2 marks)
Ans. Ethanoic/acetic acid is weak because it does not release all hydrogen in water instead it dissociates partly and achieves equilibrium with the base.
Ques. Why do esters smell sweet and how explain the process of esterification? (3 marks)
Ans. Esterification is the technique of combining an organic acid (RCOOH) with an alcohol (ROH) to shape an ester (RCOOR) and water; or a chemical reaction resulting in the formation of at least one ester product. Ester is acquired by way of an esterification response of alcohol and carboxylic acid.
When primary alcohol is handled with a carboxylic acid in the presence of sulphuric acid a compound is shaped. This compound has a sweet candy-like odor and the compound received is called an ester. The chemical reaction going on in the formation of the ester is referred to as an esterification response.
The chemical reaction of Esterification
Ques. What are the physical properties of Ethanoic acid? (5 marks)
Ans. Ethanoic Acid is an odorless clear liquid that is very pungent and has no color. The Ethanoic acid at room temperature being a lower carboxylic acid is present in the liquid state.
Ethanoic acid is absolutely soluble in water i.e why it makes vinegar. The solubility of acids in water decreases with a boom in their molecular weight. The freezing point of acetic acid is 290 K; past this temperature, it crystallizes to form glacial acetic acid.
The boiling factor of ethanoic acid is 391 K. The density of acetic acid is 1.05 g cm-3. It is denser than water which has a density of 1g cm-3. With the pH of ethanoic acid being 2.4. In its liquid form, acetic acid is polar, with a dielectric constant of 6.2. Acetic acid, which is a polar protic solvent, has a dielectric value of 6.2. The dissociation constant of Ethanoic Acid is 4.76 at 25℃.
Ques. An organic compound 'A' has the molecular formula C2H4O2 and is acidic in nature, on heating with alcohol and conc. Sulphuric acid, and vapors with pleasant or fruity smells are given out. What is this chemical compound 'A; and what is the chemical equation involved in the reaction? (CBSE All India 1999 3 marks)
Ans. The compound 'A' with molecular formula C2H4O2 is acetic acid.
- Upon heating with ethyl alcohol and concentrated sulphuric acid, Ethyl acetate is formed as the product.
- It is an ester with a pleasant or fruity smell. The reaction is known as the esterification reaction.
- The formula of esterification is CH3COOH + CH3CH2OH ⥩ CH3COOCH2CH3
Ques. An organic compound 'A' is a constituent of antifreeze and has the molecular formula C2HO6. Upon reaction with alkaline the compound 'A' is oxidized to another compound "B' with the formula C2H6O2 Identify the compounds 'A' and "B'. Write the chemical equation for the reaction, which leads to the formation of 'B'. (CBSE All India 2000 Comptt.)
Ans. The compound 'A' is ethanol, and with alkaline KMnO4, it is oxidized as ethanoic acid 'B'.
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