Aspirin Formula: Chemical Formula, Structure, Properties and Examples

The Aspirin Formula is C₉H₈O₄. Aspirin is also known as acetylsalicylic acid and contains 9 carbon atoms, 8 hydrogen atoms and 4 oxygen atoms.
Its extended molecular formula is CH₃COOC₆H₄COOH, which shows a benzene ring attached to an ester group and a carboxylic acid group.

The Aspirin Formula helps students understand the composition and structure of one of the most commonly known organic compounds in Chemistry. Aspirin is chemically called acetylsalicylic acid. Its formula C₉H₈O₄ tells the number of atoms in one molecule, while CH₃COOC₆H₄COOH gives a clearer idea of how different parts of the molecule are arranged.

In school-level Chemistry, aspirin is often discussed in organic compounds, functional groups, medicines and applied chemistry. Questions may ask students to write the chemical formula of aspirin, identify its functional groups, calculate its molecular mass or explain why it is called acetylsalicylic acid.

Key Takeaways

• Aspirin Formula: The chemical formula of aspirin is C₉H₈O₄.
• Chemical Name: Aspirin is also called acetylsalicylic acid.
• Extended Formula: The extended molecular formula is CH₃COOC₆H₄COOH.
• Functional Groups: Aspirin contains an ester group and a carboxylic acid group.
• Molecular Mass: The molecular mass of aspirin is approximately 180 u.

Aspirin Formula Structure 2026

What is Aspirin Formula?

The Aspirin Formula represents the chemical composition of aspirin, also known as acetylsalicylic acid. Its molecular formula is C₉H₈O₄.

Formula:

C₉H₈O₄

Where:

• C = carbon
• H = hydrogen
• O = oxygen

Atom count in aspirin:

• Carbon atoms = 9
• Hydrogen atoms = 8
• Oxygen atoms = 4

The formula shows that one molecule of aspirin contains a total of 21 atoms.

Chemical Formula of Aspirin

The chemical formula of aspirin is C₉H₈O₄. This formula is used to represent the exact number of carbon, hydrogen and oxygen atoms in one aspirin molecule.

C₉H₈O₄

Molecular representation:

C₉H₈O₄ = 9C + 8H + 4O

This means:

1 molecule of aspirin = 9 carbon atoms + 8 hydrogen atoms + 4 oxygen atoms

The chemical formula of aspirin is important in Chemistry because it helps students calculate molecular mass and understand the compound’s structure.

Aspirin Molecular Formula

The aspirin molecular formula is C₉H₈O₄. It gives the actual number of atoms present in one molecule of aspirin.

Total atoms:

9 + 8 + 4 = 21

So, one aspirin molecule contains 21 atoms.

The molecular formula of aspirin is used in organic chemistry, pharmaceutical chemistry and molecular mass calculations.

Aspirin Chemical Formula

The aspirin chemical formula can be written in two useful ways. The compact molecular formula gives the atom count, while the extended formula shows the structure more clearly.

Compact formula:

C₉H₈O₄

Extended formula:

CH₃COOC₆H₄COOH

The extended formula CH₃COOC₆H₄COOH shows that aspirin has:

• A methyl group, CH₃
• An ester linkage, COO
• A benzene ring, C₆H₄
• A carboxylic acid group, COOH

This is why aspirin formula chemistry is connected with both aromatic compounds and functional groups.

Acetylsalicylic Acid Formula

Aspirin is chemically known as acetylsalicylic acid. The acetylsalicylic acid formula is C₉H₈O₄.

Formula:

C₉H₈O₄

Extended formula:

CH₃COOC₆H₄COOH

The name acetylsalicylic acid comes from the acetyl group attached to salicylic acid. In simple terms, aspirin is formed when salicylic acid is acetylated.

Basic reaction:

Salicylic acid + Acetic anhydride → Aspirin + Acetic acid

Formula-based representation:

C₇H₆O₃ + C₄H₆O₃ → C₉H₈O₄ + C₂H₄O₂

Here:

• C₇H₆O₃ = salicylic acid
• C₄H₆O₃ = acetic anhydride
• C₉H₈O₄ = aspirin
• C₂H₄O₂ = acetic acid

Aspirin Structure

Aspirin structure contains a benzene ring attached to two important functional groups: a carboxylic acid group and an ester group.

Extended structural formula:

CH₃COOC₆H₄COOH

Main parts of aspirin structure:

The benzene ring gives aspirin its aromatic compound structure. The carboxylic acid group gives acidic behaviour, while the ester group is formed during acetylation.

Aspirin Compound Formula

The aspirin compound formula is C₉H₈O₄. Aspirin is an organic compound because it contains carbon and hydrogen along with oxygen.

Formula:

C₉H₈O₄

Aspirin belongs to the class of organic compounds because it has:

• Carbon atoms
• Hydrogen atoms
• Oxygen atoms
• Aromatic ring structure
• Functional groups

It is also considered an aromatic compound because of the benzene ring present in its structure.

Functional Groups in Aspirin Formula

The aspirin formula CH₃COOC₆H₄COOH shows two major functional groups. These groups decide the chemical behaviour of aspirin.

The carboxylic acid group can donate a proton, while the ester group affects aspirin’s reactivity and structure.

Molecular Mass of Aspirin

The molecular mass of aspirin can be calculated using its formula C₉H₈O₄. Use atomic masses: carbon = 12, hydrogen = 1 and oxygen = 16.

Formula:

C₉H₈O₄

Calculation:

Molecular mass = (9 × 12) + (8 × 1) + (4 × 16)

Molecular mass = 108 + 8 + 64

Molecular mass = 180 u

So, the molecular mass of aspirin is:

180 u

In molar mass form:

180 g/mol

This value is useful in Chemistry numericals based on mole concept, molar mass and pharmaceutical compounds.

Preparation of Aspirin Formula

Aspirin is commonly prepared by reacting salicylic acid with acetic anhydride. This reaction is called acetylation because an acetyl group is added to salicylic acid.

Word equation:

Salicylic acid + Acetic anhydride → Aspirin + Acetic acid

Chemical equation:

C₇H₆O₃ + C₄H₆O₃ → C₉H₈O₄ + C₂H₄O₂

In this reaction:

• Salicylic acid provides the base aromatic structure.
• Acetic anhydride provides the acetyl group.
• Aspirin is formed as the main product.
• Acetic acid is formed as a by-product.

This reaction helps explain why aspirin is called acetylsalicylic acid.

Aspirin Formula in Organic Chemistry

In organic chemistry, aspirin is used as an example of a compound containing more than one functional group. It connects concepts such as aromatic compounds, esters and carboxylic acids.

Aspirin formula chemistry includes:

• Molecular formula: C₉H₈O₄
• Extended formula: CH₃COOC₆H₄COOH
• Functional groups: ester and carboxylic acid
• Aromatic ring: C₆H₄
• Chemical name: acetylsalicylic acid

This makes aspirin useful for understanding how structure affects properties in organic compounds.

Aspirin Uses

Aspirin uses are usually discussed in applied chemistry, medicine and pharmaceutical chemistry. It is widely known as a medicinal compound.

Common aspirin uses include:

• It is used as a pain-relieving medicine.
• It is used to reduce fever.
• It is used as an anti-inflammatory compound.
• It is studied as an example of an organic medicinal compound.
• It helps students understand pharmaceutical chemistry.

Medical use of aspirin should always follow advice from a qualified healthcare professional, especially for children, pregnant people or people with bleeding disorders, ulcers or aspirin allergy.

How to Write Aspirin Formula

Aspirin Formula questions usually ask students to write the molecular formula, extended formula, atom count or functional groups.

Steps:

1. Write the molecular formula:

C₉H₈O₄

1. Count atoms from the formula:

C = 9, H = 8, O = 4

1. Write the extended formula if structure is asked:

CH₃COOC₆H₄COOH

1. Identify functional groups:

Ester group and carboxylic acid group

1. Write the chemical name:

Acetylsalicylic acid

This format is useful for school-level Chemistry answers.

Solved Examples on Aspirin Formula

Aspirin Formula questions usually test molecular formula, atom count, molecular mass and functional groups. These examples follow common school exam patterns.

Example 1: Write the chemical formula of aspirin

Answer:

The chemical formula of aspirin is:

C₉H₈O₄

It contains:

• 9 carbon atoms
• 8 hydrogen atoms
• 4 oxygen atoms

Example 2: Write the extended molecular formula of aspirin

Answer:

The extended molecular formula of aspirin is:

CH₃COOC₆H₄COOH

This formula shows a benzene ring attached to an ester group and a carboxylic acid group.

Example 3: Find the molecular mass of aspirin

Given:

Formula of aspirin:

C₉H₈O₄

Atomic masses:

C = 12

H = 1

O = 16

Calculation:

Molecular mass = (9 × 12) + (8 × 1) + (4 × 16)

Molecular mass = 108 + 8 + 64

Molecular mass = 180 u

Answer:

The molecular mass of aspirin is 180 u.

Example 4: Find the total number of atoms in aspirin

Given formula:

C₉H₈O₄

Atom count:

Carbon = 9

Hydrogen = 8

Oxygen = 4

Total atoms:

9 + 8 + 4 = 21

Answer:

One molecule of aspirin contains 21 atoms.

Example 5: Identify the functional groups in aspirin

Given extended formula:

CH₃COOC₆H₄COOH

Functional groups:

• Ester group: −COO−
• Carboxylic acid group: −COOH

Answer:

Aspirin contains an ester group and a carboxylic acid group.

Common Mistakes in Aspirin Formula

Many aspirin formula mistakes happen when students confuse aspirin with salicylic acid. Aspirin and salicylic acid have different formulas.

Important checks:

• Use C₉H₈O₄ for aspirin.
• Use CH₃COOC₆H₄COOH as the extended formula.
• Remember that aspirin is acetylsalicylic acid.
• Identify both ester and carboxylic acid groups.
• Count total atoms as 21.
• Use 180 u as the approximate molecular mass of aspirin.
• Do not write salicylic acid formula C₇H₆O₃ as aspirin formula.

In formula-based questions, check whether the question asks for aspirin, salicylic acid or acetylsalicylic acid.

Applications of Aspirin Formula

The Aspirin Formula is useful in Chemistry, Biology, medicine and pharmaceutical science. It helps students connect molecular formula with structure and function.

Main applications:

• It helps identify aspirin as acetylsalicylic acid.
• It supports molecular mass calculations.
• It explains the structure of aspirin.
• It helps students identify ester and carboxylic acid groups.
• It connects organic chemistry with medicines.
• It supports questions on pharmaceutical compounds.
• It helps compare aspirin with salicylic acid.