Alcohols & Carboxylic Acids - Free MCQ Practice Test with solutions, UPSC

When an aldehyde is oxidised, the product formed is a carboxylic acid.

Key points to understand this process:

• Oxidation involves the addition of oxygen or the removal of hydrogen.
• Aldehydes are converted to carboxylic acids through oxidation.
• Common oxidising agents include alkaline potassium permanganate and acidified potassium dichromate.

These agents facilitate the transformation by providing the necessary conditions for the reaction.

Hydrogen gas is released.

Sulphuric acid is used as a dehydrating agent because sulphuric acid has a great affinity for water. It readily removes elements of water from other compounds i.e, it acts as a dehydrating agent, it being a hygroscopic substance absorbs water from other substances without dissolving in it, so it is considered a good drying agent.

Acetic acid, systematically named ethanoic acid, is a colourless liquid organic compound with the chemical formula 
CH3COOH .

Carboxylic acid is a weak acid as it undergoes partial or incomplete dissociation in water.

This is an esterification reaction in which a sweet smelling compound ester is formed.

Ethanoic acid is commonly known as acetic acid. It is a carboxylic acid with the chemical formula CH₃COOH and is widely recognised for its presence in vinegar, where it contributes to the sour taste and smell.

The other options represent different acids:

• Formic acid (methanoic acid)
• Propanoic acid
• Picric acid (trinitrophenol)

The dehydration of ethanol to ethene involves the removal of water.

• This process is a chemical reaction where ethanol loses a water molecule.
• The reaction typically requires a catalyst, such as concentrated sulphuric acid.
• During dehydration, ethanol (C₂H₅OH) is converted into ethene (C₂H₄), releasing water (H₂O).

Ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid as a catalyst to produce the ester, ethyl ethanoate.

Ethanoic acid is called glacial acetic acid because:

• It solidifies into a solid form in cold weather, around 16.7°C (62°F).
• This solid form resembles a glacier, giving rise to the name.