Ethanoic Acid - Overview, Structure, Properties & Uses, Preparation, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:33 PM IST

What is the formula of Ethanoic Acid?

The carboxylic acid family consists of two carbon acids: ethanolic acid (also known as Acetic acid) and methanolic acid (which is a one-carbon carboxylic acid). Nonetheless, its IUPAC name may also be mentioned as acetic acid through many sources, despite the fact that its correct IUPAC name is ethanoic acid. The chemical formula of Ethanoic acid or Ethanoic acid formula is CH₃COOH.Ethanoic acid is a common household substance used in kitchens that can be diluted in water to create vinegar with a concentration of 5-8%. A common lab chemical, ethanoic acid freezes in winter and forms a glacier-like appearance. For this reason, it is also sometimes called glacial acetic acid. Ethanoic acid is also known as Acetic acid.

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What is the formula of Ethanoic Acid?
Structural Formula of Ethanoic Acid:
A chemical analysis of ethanol (reactions of ethanol)
Methods of Preparation of Ethanoic acid
Uses of Ethanoic Acid

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Structural Formula of Ethanoic Acid:

Condensed ethanoic acid formula CH3COOH, which can be written as C₂H₄O₂ or CH₃CO₂H in its condensed form. Molar mass (or molecular mass) of the compound is 60,05 g / mol.

Despite its simple and elementary structure, ethanoic acid is still one of the simplest carboxylic acids after ethanoic acid. It consists of a carboxylic acid functional group (–COOH) attached to a methyl group (–CH₃). There is the possibility that it also has a hydroxyl group (–OH) tying it together with an acetyl group (–CH₃CO).

SP2 hybridization is present. In liquid and vapour form, Ethanoic acid is typically found as dimers due to hydrogen bonds that form between two molecules of the acid. As a result of this electron cloud attraction, the more electronegative oxygen atom of the carboxylic acid group forms a hydrogen bond with the lesser electronegative hydrogen atom.

Properties of Ethanoic Acid

Chemical formula	CH₃COOH
Molecular Weight/ Molar Mass	60.05 g/mol
Density	1.05 g/cm³
Boiling Point	118oC
Melting Point	16oC

An overview of ethanol's physical properties

Purified ethanol is a colourless and clear liquid with an unmistakable odour:
Ethanoic acid is flash pointed at 39 degrees Celsius.
Ethanoic acid has a density of 1.05 grams per cubic centimetre.
There is a boiling point of 118°C for Ethanoic acid and a melting point of 16°C for Ethanoic acid.
Hydrogen bonds are present in ethanol through one donor atom and two acceptor atoms.
Water dissolves pure ethanoic acid in a concentration of >100 mg/mL at 25°C. According to this doctrine, it will dissolve in water at all concentrations.
Sodium tetrachloride and sodium disulphide are both fully soluble in ethanol. Aqueous solutions in organic solvents such as ethyl ether, benzene, acetone, glycerol and ethanol can be dissolved in them.
When the temperature is 25 degrees Celsius, ethanol has a vapor pressure of 15.7 mmHg.
Ethanoic acid has a Log P of -0.17.
The temperature at which ethanoic acid is stored in a laboratory, as well as other storage conditions, are usually stable.
Assuming a temperature of 25°C, ethanol has a viscosity of 1.056 mPa-s.
A 25°C solution of ethanol has a surface tension of 27.10 m N/m.
A mol of ethanolic acid burns at 874.2 kJ / mol.
Considering 25°C as the vaporization temperature, Ethanoic acid has a heat of vaporisation of 23.36.
Ethanoic acid solution at 1.0 molar pH has a pH of 2.4.
Ethanoic acid has a p Ka of 4.76 at 25°C (dissociation constant).

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A chemical analysis of ethanol (reactions of ethanol)

Esters are formed when carboxylic acids react with alcoholic compounds to form a new class of chemical compounds. Esterification is the chemical reaction that produces esters. Following is an example of what happens when Ethanoic acid (a carboxylic acid) reacts with Ethanol (ethyl alcohol) to form Ethyl Ethanoate (an ester):

CH₃COOH + CH₃CH₂OH → CH₃COOCH₂CH₃

(Ethanoic acid) (Ethanol) (Ethyl Ethanoate)

It can be identified easily by their characteristic fruity aroma that the newest class of chemical compounds (Esters) are made of. In the food industry, esters can be used as food flavourings, while in the perfume industry, they can produce good fragrances.

In addition, esters are commonly used in the production of soap. The molecular structure of soap is formed when esters react with bases (particularly alkalis). Saponification is the reaction that occurs in this case. The reaction is generally carried out with higher molecular weight esters. The following information can be utilized to understand the saponification reaction:

RCOOR’ + NaOH → RCOO–Na+ + R’OH

(An ester) (Sodium hydroxide) (Soap) (Alcohol)

Analogous to a weak acid, ethanoic acid reacts with bases. A salt molecule and a molecule of water are formed when the acid reacts with a base. A chemical reaction between ethanoic acid and sodium hydroxide (a base) is shown below: it produces sodium ethanoate and water when ethanoic acid reacts with sodium hydroxide:

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CH₃COOH + NaOH → CH₃COONa + H₂O

(Ethanoic acid) (Sodium (Sodium (water) hydroxide) ethanoate)

As a result of this reaction, a salt is formed (Sodium ethanoate) that has a wide range of industrial applications including the textile industry to neutralize sulfuric acid (a cleaning agent for fibres), in the food industry as a preservative, a mild seasoning and flavouring agent, and as a buffer agent along with ethanoic acid (a buffer for maintaining the pH of a medium).

Carbonates: The reaction of ethanoic acid with carbonates or their hydrogen derivatives, called hydrogen carbonates (also referred to as bicarbonates), creates salt, along with carbon dioxide and water by-products. Following are examples of reactions between ethanol and sodium carbonate or sodium bicarbonate:

2CH₃COOH + Na₂CO₃ → 2CH₃COONa + CO₂ + H₂O

(Ethanoic acid) (Sodium (Sodium (carbon (water)

Carbonate) ethanoate) dioxide)

CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O

(Ethanoic acid) (Sodium (Sodium (carbon (water) bicarbonate) ethanoate) dioxide)

It has been shown that ethanoic acid forms carboxylic acid derivatives through reactions with a number of other reagents, which have been classified as a separate class of organic chemicals referred to as carboxylic acid derivatives. There are several kinds of acid chlorides, acid anhydrides, ester and amide compounds.

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Chlorides of acid: The reaction between ethanoic acid and thionyl chloride (SOCl₂) leads to the formation of acetyl chloride. The following is an explanation for this reaction:

CH₃COOH + SOCl₂ → CH₃COCl +HCl + SO₂

(Ethanoic acid) (Thionyl (Acetyl (Hydrochloric (Sulphur Chloride) Chloride) Acid) Dioxide)

Acetic Anhydride is formed when Ethanoic acid reacts with an acid chloride in the presence of a base. The following is an explanation for this reaction:

CH₃COOH + CH₃COCl → (CH₃CO)₂O + HCl

(Ethanoic acid) (Acetyl (Acetic (Hydrochloric Chloride) Anhydride) Acid)

Ester: Described under the Esterification reaction, this reaction is the transformation of ester into ester.

Ethanoic acid forms dimethyl amide when it reacts with methylamine in the presence of di cyclohexyl carbodiimide (DCC). In response, the following reaction occurs in the body:

CH₃COOH + NH₂CH₃ → CH₃CONHCH₃ + H₂O

(Ethanoic acid) (Methyl (N-methyl (Water) Imine) Acetamide)

NCERT Chemistry Notes :

Methods of Preparation of Ethanoic acid

Carbonylation of methanol is a common means of preparing ethanol. A metal carbonyl catalyst is used in this reaction to react methanol with carbon monoxide to form acetic acid.

Uses of Ethanoic Acid

As a solvent, it is utilized for a variety of reactions requiring protic solvents.

Synthetic polymers and vinegar are produced by using it.

As a lysing agent for blood cells, it is used in laboratories.

As an antifungal agent, it is used.

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Frequently Asked Questions (FAQs)

1. Q1. Ethanoic acid: Why is it used?

As part of printing processes, acetates like metal and vinyl are used; cellulose acetate, used in textiles and photographic films, is made of acetate; and volatile organic esters are made from acetate.

2. Q2. Food can be preserved with ethanoic acid?

Salad dressings are not the only application for acetic acid. Various foods are preserved with this ingredient as natural preservatives and antibacterial, such as vegetable pickles and edible films.

3. Q3. What is the difference between ethanol and vinegar?

Acetic acid, also known as ethanoic acid, is simply ethanoic acid diluted in water. The majority of ethanoic acid is now synthesized and used in the production of plastics and other fundamental materials.

4. Q4. What makes ethanol an acid that is weak?

Weak acids, such as ethanoic acid (acetic acid), are those in which their hydrogen has not been completely released into water. This results in a partial dissociation and equilibrium with its conjugate base.

5. Q5. What is the reason for the sweet smell of esters?

Acetic acid and ethanol produce a sweet aroma with their ester. Esters interact modestly with each other. A smaller intermolecular force of attraction makes ester compounds volatile. - Esters do not have hydrogen bonds.

6. How does ethanoic acid participate in esterification reactions?

Ethanoic acid undergoes esterification by reacting with alcohols in the presence of an acid catalyst. The carboxyl group of ethanoic acid combines with the hydroxyl group of the alcohol, eliminating water and forming an ester. For example, ethanoic acid reacts with ethanol to form ethyl ethanoate (ethyl acetate), a common solvent.

7. What is the relationship between ethanoic acid and acetyl groups in organic synthesis?

Ethanoic acid is the source of acetyl groups (CH3CO-) in many organic reactions. The acetyl group can be introduced into molecules through various reactions, such as acetylation using acetic anhydride or acetyl chloride (both derived from ethanoic acid). This is important in the synthesis of many pharmaceuticals and other organic compounds.

8. How does ethanoic acid react with bases, and what products are formed?

Ethanoic acid reacts with bases to form salts called acetates. For example, with sodium hydroxide, it forms sodium acetate and water: CH3COOH + NaOH → CH3COONa + H2O. The acetate ion (CH3COO-) is the conjugate base of ethanoic acid. These reactions are examples of acid-base neutralization and are important in various chemical processes.

9. What is the significance of ethanoic acid's dissociation constant (Ka)?

The dissociation constant (Ka) of ethanoic acid is approximately 1.8 × 10^-5 at room temperature. This value indicates the extent to which the acid dissociates in water. The relatively low Ka value confirms that ethanoic acid is a weak acid, meaning it only partially dissociates in solution. This property is crucial for its use in buffer solutions and its behavior in various chemical reactions.

10. How does temperature affect the properties of ethanoic acid?

Temperature significantly affects ethanoic acid's properties. As temperature increases, its viscosity decreases, and its ability to dissociate in water increases slightly. The freezing point of pure ethanoic acid is about 16.6°C (61.9°F), which is why it's often called glacial acetic acid when in its pure, ice-like form at room temperature.

11. How is ethanoic acid prepared industrially?

Industrially, ethanoic acid is primarily produced through methanol carbonylation. This process involves reacting methanol with carbon monoxide in the presence of a rhodium catalyst. Other methods include oxidation of acetaldehyde or ethanol, and fermentation of ethanol by acetic acid bacteria.

12. How does the acidity of ethanoic acid compare to other carboxylic acids?

Ethanoic acid is generally less acidic than carboxylic acids with longer carbon chains or electron-withdrawing groups. For example, it's less acidic than propanoic acid (CH3CH2COOH) but more acidic than formic acid (HCOOH). The acidity is influenced by factors such as inductive effects and the stability of the conjugate base.

13. What is the boiling point of ethanoic acid, and how does it compare to similar compounds?

The boiling point of ethanoic acid is about 118°C (244°F), which is relatively high for a molecule of its size. This high boiling point is due to strong intermolecular hydrogen bonding. It's significantly higher than that of ethanol (78°C) or acetone (56°C), which have similar molecular weights but weaker intermolecular forces.

14. What is the significance of ethanoic acid's pKa value?

The pKa value of ethanoic acid is approximately 4.76, which indicates its strength as an acid. This value represents the negative logarithm of the acid dissociation constant (Ka). The pKa is important because it helps predict the acid's behavior in solution, its ability to react with bases, and its effectiveness as a buffer component.

15. How does ethanoic acid behave in aqueous solutions?

In aqueous solutions, ethanoic acid partially dissociates to form hydronium ions (H3O+) and acetate ions (CH3COO-). It establishes an equilibrium: CH3COOH + H2O ⇌ CH3COO- + H3O+. The solution is acidic, with a pH typically between 2 and 3, depending on the concentration. Ethanoic acid can also act as a buffer in certain concentration ranges.

16. How does the structure of ethanoic acid contribute to its properties?

The structure of ethanoic acid consists of a carboxyl group (-COOH) attached to a methyl group (-CH3). The carboxyl group is responsible for its acidic properties and ability to form hydrogen bonds. This structure allows ethanoic acid to participate in various reactions, including esterification and acid-base reactions, and contributes to its solubility in water and polar solvents.

17. How does the structure of ethanoic acid allow it to form dimers?

Ethanoic acid molecules can form dimers through hydrogen bonding between their carboxyl groups. Two ethanoic acid molecules align so that the hydrogen of one molecule's -OH group bonds with the oxygen of the other molecule's C=O group, and vice versa. This dimerization is particularly prevalent in the gas phase and non-polar solvents.

18. What is the significance of ethanoic acid's dipole moment?

Ethanoic acid has a dipole moment of about 1.74 D (Debye units), which arises from the polar carboxyl group (-COOH). This dipole moment contributes to ethanoic acid's ability to dissolve in polar solvents like water and its tendency to form hydrogen bonds. The dipole moment also influences its boiling point and other physical properties.

19. How does ethanoic acid behave in non-aqueous solvents?

In non-aqueous solvents, especially non-polar ones, ethanoic acid tends to form dimers through hydrogen bonding between two molecules. This dimerization can affect its reactivity and physical properties. In polar aprotic solvents like acetone or dimethyl sulfoxide, ethanoic acid may behave more as a single molecule but can still participate in hydrogen bonding with the solvent.

20. How does the presence of ethanoic acid affect the pH of buffer solutions?

Ethanoic acid, combined with its conjugate base (acetate), forms an effective buffer solution. This buffer can maintain a relatively stable pH (around 4.76, the pKa of ethanoic acid) when small amounts of acid or base are added. The buffering action is due to the equilibrium between the acid and its conjugate base: CH3COOH ⇌ CH3COO- + H+. This property is useful in various biological and chemical applications.

21. What is ethanoic acid and why is it important in organic chemistry?

Ethanoic acid, also known as acetic acid, is a simple carboxylic acid with the formula CH3COOH. It's important in organic chemistry because it serves as a prototype for carboxylic acids, demonstrating key properties and reactions of this functional group. Ethanoic acid is widely used in industry and everyday life, from vinegar production to synthetic fiber manufacturing.

22. What is the difference between glacial acetic acid and vinegar?

Glacial acetic acid is pure, water-free ethanoic acid (99.5% or higher concentration). Vinegar, on the other hand, is a dilute solution of ethanoic acid in water, typically containing 4-8% acetic acid. Glacial acetic acid is much more corrosive and dangerous to handle than vinegar, which is safe for culinary use.

23. What is the role of ethanoic acid in the production of vinyl acetate?

Ethanoic acid is a key reactant in the production of vinyl acetate, an important industrial chemical. The process involves reacting ethanoic acid with ethylene and oxygen over a palladium catalyst. Vinyl acetate is used to produce polyvinyl acetate, which is used in adhesives, paints, and other products.

24. Why is ethanoic acid considered a weak acid?

Ethanoic acid is considered a weak acid because it only partially dissociates in water. This means that in an aqueous solution, only a small fraction of ethanoic acid molecules ionize to form hydrogen ions (H+) and acetate ions (CH3COO-). The weak acidity is due to the limited stability of the acetate ion, which can readily accept a proton to reform the acid.

25. How does ethanoic acid form hydrogen bonds, and why is this important?

Ethanoic acid forms hydrogen bonds through its carboxyl group (-COOH). The hydrogen of the -OH group can form hydrogen bonds with oxygen atoms of other ethanoic acid molecules or with water molecules. This hydrogen bonding is crucial for explaining ethanoic acid's physical properties, such as its relatively high boiling point and its miscibility with water.

26. What is the significance of ethanoic acid's ability to form a azeotrope with water?

Ethanoic acid forms an azeotrope with water at 79.1% acid by weight, boiling at 100.6°C. This azeotropic mixture is significant because it means that simple distillation cannot be used to obtain pure ethanoic acid from dilute solutions. Understanding this property is crucial in industrial purification processes and in laboratory techniques for handling ethanoic acid solutions.

27. What is the significance of ethanoic acid's vapor pressure?

The vapor pressure of ethanoic acid is relatively low compared to water, about 11.4 mmHg at 20°C. This low vapor pressure contributes to its high boiling point and affects its evaporation rate. Understanding the vapor pressure is crucial in industrial applications, especially in distillation processes and in designing storage and handling systems for ethanoic acid.

28. What is the significance of ethanoic acid in biochemistry?

In biochemistry, ethanoic acid plays several important roles. It's a key intermediate in metabolism, particularly in the form of acetyl-CoA, which is central to the citric acid cycle and fatty acid synthesis. Acetate (the conjugate base of ethanoic acid) is also involved in various biological processes, including histone acetylation in gene regulation.

29. How does ethanoic acid contribute to the taste and preservation of vinegar?

Ethanoic acid is the main component responsible for vinegar's sour taste and preservative properties. Its acidity inhibits the growth of many microorganisms, making vinegar useful for food preservation. The characteristic flavor of vinegar comes from the combination of ethanoic acid with other compounds produced during fermentation.

30. What safety precautions should be taken when handling concentrated ethanoic acid?

Concentrated ethanoic acid (glacial acetic acid) is corrosive and can cause severe burns. Safety precautions include wearing protective gloves, goggles, and clothing, working in a well-ventilated area, and avoiding inhalation of vapors. In case of skin contact, the affected area should be washed immediately with plenty of water.

31. What is the role of ethanoic acid in the production of cellulose acetate?

Ethanoic acid is used in the production of cellulose acetate, a important material in textiles and plastics. The process involves reacting cellulose with acetic anhydride (derived from ethanoic acid) in the presence of sulfuric acid. The resulting cellulose acetate is used in products like photographic film, eyeglass frames, and cigarette filters.

32. How does ethanoic acid behave as a solvent?

Ethanoic acid is a polar protic solvent, capable of dissolving both polar and some non-polar compounds. It can dissolve many organic compounds and some inorganic salts. Its ability to form hydrogen bonds makes it particularly effective at dissolving polar substances. However, its corrosive nature limits its use as a solvent in many applications.

33. What is the role of ethanoic acid in the production of aspirin?

Ethanoic acid is a key reagent in the synthesis of aspirin (acetylsalicylic acid). It reacts with salicylic acid in a process called acetylation. The reaction involves the replacement of a hydrogen atom in salicylic acid with an acetyl group (CH3CO-) derived from ethanoic acid. This reaction is typically carried out using acetic anhydride, which is derived from ethanoic acid.

34. How does ethanoic acid contribute to the acidity of vinegar-based foods?

Ethanoic acid is the primary component responsible for the acidity of vinegar-based foods. It lowers the pH of these foods, contributing to their tart flavor and helping to preserve them by inhibiting bacterial growth. The typical pH of vinegar ranges from 2 to 3, depending on the concentration of ethanoic acid, which is usually between 4% and 8% in culinary vinegars.

35. What is the importance of ethanoic acid in the production of polyethylene terephthalate (PET)?

Ethanoic acid plays an indirect but crucial role in the production of polyethylene terephthalate (PET), a common plastic used in bottles and synthetic fibers. It's used to produce terephthalic acid, one of the monomers for PET synthesis. The process involves oxidizing p-xylene to terephthalic acid using acetic acid as a solvent and catalyst carrier.

36. How does ethanoic acid participate in redox reactions?

Ethanoic acid can participate in redox reactions, although it's not as readily oxidized or reduced as some other organic compounds. It can be reduced to acetaldehyde (CH3CHO) or ethanol (CH3CH2OH) under certain conditions. Conversely, ethanoic acid is the product of the oxidation of ethanol, a reaction that occurs naturally in the production of vinegar.

37. What is the role of ethanoic acid in the acetylation of amines?

Ethanoic acid, usually in the form of acetic anhydride or acetyl chloride, is used to acetylate amines. This reaction introduces an acetyl group (CH3CO-) onto the nitrogen atom of the amine. Acetylation of amines is important in organic synthesis, particularly in the production of pharmaceuticals and dyes. For example, acetylation of aniline produces acetanilide, a precursor to many drugs.

38. How does ethanoic acid contribute to the formation of esters in fruits?

Ethanoic acid, along with other carboxylic acids, reacts with alcohols naturally present in fruits to form esters. These esters contribute to the characteristic flavors and aromas of many fruits. For instance, ethyl acetate, formed from ethanoic acid and ethanol, is found in many fruits and contributes to their fruity smell. This esterification process occurs naturally during fruit ripening.

39. How does ethanoic acid interact with metals, and what are the products?

Ethanoic acid reacts with many metals to form metal acetates and hydrogen gas. The general reaction is: 2CH3COOH + M → (CH3COO)2M + H2, where M is a metal. For example, with zinc: 2CH3COOH + Zn → (CH3COO)2Zn + H2. This reaction is more vigorous with more reactive metals like sodium or potassium. The reaction with iron is the basis for rust removal using vinegar.

40. What is the role of ethanoic acid in the production of synthetic fibers?

Ethanoic acid is crucial in the production of various synthetic fibers. It's used in the manufacture of cellulose acetate fibers, where cellulose is treated with acetic anhydride (derived from ethanoic acid). Additionally, it's used as a solvent and reagent in the production of polyester fibers, particularly in the synthesis of terephthalic acid, a key monomer in polyester production.

41. What is the mechanism of ethanoic acid's reaction in Fischer esterification?

In Fischer esterification, ethanoic acid reacts with an alcohol to form an ester and water. The mechanism involves protonation of the carbonyl oxygen by an acid catalyst, nucleophilic attack by the alcohol, proton transfer, and loss of water. The rate-determining step is typically the nucleophilic addition of the alcohol to the protonated carbonyl group. This reaction is reversible and reaches equilibrium unless the water is removed.

42. How does ethanoic acid contribute to the preservation of food?

Ethanoic acid acts as a food preservative due to its ability to lower pH and inhibit microbial growth. It creates an acidic environment that many harmful bacteria cannot tolerate. Additionally, the undissociated form of the acid can penetrate bacterial cell membranes, disrupting cellular functions. This preservative action is why vinegar (dilute ethanoic acid) is used in pickling and other food preservation techniques.