medium importancemedium difficulty5 min

Ethanoic Acid

Ethanoic acid is a carboxylic acid with formula CH₃COOH.

In one line: COOH at the end means acid.

Practice This Concept

Understand it

Ethanoic acid is the acid found in vinegar in dilute form.
Its special group is -COOH, which gives acidic properties.
It reacts with bases and carbonates, so it is an important example for understanding acid behaviour in organic chemistry.
Students should also remember that it is a weak acid, not a strong mineral acid.

Example

CH₃COOH reacts with sodium hydrogen carbonate to release carbon dioxide gas, showing its acidic nature.

Rule to remember

Ethanoic acid has the formula CH₃COOH.

The key group is -COOH.

It reacts with bases and carbonates, and it is a weak acid compared with mineral acids.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

1When ethanoic acid reacts with sodium hydrogen carbonate, carbon dioxide gas is released.
2This reaction is commonly used to show the presence of an acid in school experiments.

Method you can reuse

1Locate the -COOH group.
2Name the compound as a carboxylic acid.
3Recall its acidic reactions.
4Distinguish it from ethanol by the presence of the carboxyl group.

Sketch it in your answer

Write the structure as CH3-C(=O)-OH so the carboxyl group is easy to see.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Which functional group gives ethanoic acid its acidic nature?

Think first, then show answer

The carboxyl group -COOH gives ethanoic acid its acidic nature. That group is the main reason the compound behaves like an acid.

Common wrong answer

A common wrong answer is to identify CH₃CH₂OH as ethanoic acid.

Why it loses marks: It is ethanol and does not contain -COOH.

Don't mix this up

Students often confuse ethanoic acid with ethanol because both contain carbon, hydrogen, and oxygen.

Exam tip

Whenever you see -COOH, think carboxylic acid and acidic behaviour.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions may ask for the formula, the functional group, the reaction with carbonates, or the difference between ethanol and ethanoic acid.

1
Enough for 1 mark
Ethanoic acid is a carboxylic acid with formula CH₃COOH.
2
Add for 2 marks
Example: CH₃COOH reacts with sodium hydrogen carbonate to release carbon dioxide gas, showing its acidic nature.
3
Add for 3 marks
Ethanoic acid is the acid found in vinegar in dilute form.

MCQ Quiz

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