Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

The conversion of ethanol (C2H5OH) to ethanoic acid (CH3COOH), commonly known as acetic acid, is considered an oxidation reaction. In this process, ethanol undergoes oxidation, and oxygen gains electrons. Let’s break down the reaction to understand why it is classified as an oxidation reaction:

The balanced chemical equation for the conversion of ethanol to ethanoic acid is as follows:

C₂H₅OH + O₂ → CH₃COOH + H₂O

1. Initial State (Ethanol): Ethanol is the starting material with the molecular formula C2H5OH.

2. Addition of Oxygen (O₂): In the presence of oxygen (O₂), ethanol undergoes oxidation. One of the carbon atoms in ethanol goes from a +3 oxidation state (in ethanol) to a +4 oxidation state (in ethanoic acid).

3. Formation of Ethanoic Acid: The product of the reaction is ethanoic acid (CH3COOH), which contains a carbonyl group (C=O). The hydrogen in the hydroxyl group of ethanol is replaced by an oxygen atom.

4. Water as a Byproduct: Water (H₂O) is formed as a byproduct of the reaction.

The key indicator of oxidation is the increase in the oxidation state of the carbon atom. In the case of ethanol to ethanoic acid conversion, the carbon in the methyl group (CH₃) undergoes an increase in its oxidation state from +3 to +4. This change reflects the loss of electrons by the carbon atom, making it more oxidized.

In summary, the conversion of ethanol to ethanoic acid involves the addition of oxygen, resulting in the oxidation of ethanol. The change in oxidation state of carbon from a lower to a higher value is a characteristic feature of oxidation reactions.