Question

Molecular formula of acetic acid is
A. \[{{\text{C}}_{2}}{{\text{H}}_{4}}{{\text{O}}_{2}}\]
B. \[{{\text{C}}_{3}}{{\text{H}}_{4}}{{\text{O}}_{2}}\]
C. \[\text{C}{{\text{H}}_{4}}{{\text{O}}_{2}}\]
D. None

Answer 1

Hint: The acetic acid is considered weak acid which is also known as ethanoic acid. Acetic acid consists of a carboxylic acid along with the methyl group. Vinegar is another name for the acetic acid which is commonly used in the food.

Complete step by step answer:
- In the given question, we have to identify the correct molecular formula of acetic acid.
- As the name tells it is an acidic but weak acid.
- As we know that acetic acid is also known as ethanoic acid so it means that it contains two carbon atoms.
- Because while naming any organic compound the word 'eth' is used when there are two carbon atoms present whereas 'meth' is used for only one carbon atom.
- Also, the formula of the carboxylic acid group is $\text{-COOH}$.
- So, the molecular formula of acetic acid will be $\text{C}{{\text{H}}_{3}}\text{COOH}$ as we can see that the carboxylic group is present along with one methyl group that is $\text{C}{{\text{H}}_{3}}-$.
- Whereas in option B and C, there is a presence of only 3 and 1 carbon atom respectively.
- So, the name of the compound \[{{\text{C}}_{3}}{{\text{H}}_{4}}{{\text{O}}_{2}}\] is methylglyoxal and commonly known as acrylic acid.
- Whereas the name of the compound \[\text{C}{{\text{H}}_{4}}{{\text{O}}_{2}}\] is methyl hyperoxide.
So, the correct answer is “Option A”.

Note: The preparation of acetic acid is done by using methanol with carbon monoxide in which rhodium - iodide is used as a catalyst. The glacial acetic acid term is used for the pure acetic acid which is commonly corrosive and miscible in water.