Oxidation Reaction Identification

This question asks us to identify an example of an oxidation reaction from the given choices. An oxidation reaction is a type of chemical reaction that involves the loss of electrons by a substance or an increase in its oxidation state. Let's analyze each option:

Analyzing Reaction Options

• Option 1: Freezing of water

  Freezing is a physical change where liquid water (\(H_2O\)) turns into solid ice (\(H_2O\)). The chemical composition and oxidation states of hydrogen (usually +1) and oxygen (usually -2) do not change. This is a phase transition, not a chemical reaction involving oxidation.

• Option 2: Dissolving sugar in water

  Dissolving sugar (like sucrose, \(C_{12}H_{22}O_{11}\)) in water is a physical process. The sugar molecules disperse throughout the water, forming a solution. No chemical bonds are broken or formed in a way that constitutes an oxidation or reduction reaction.

• Option 3: Rusting of iron

  Rusting is a common example of an oxidation reaction. It occurs when iron (Fe) reacts with oxygen (\(O_2\)) in the presence of moisture. The iron metal loses electrons and its oxidation state increases, forming iron oxides (rust, typically \(Fe_2O_3 \cdot nH_2O\)). The simplified half-reaction for iron oxidation is \(Fe \rightarrow Fe^{2+} + 2e^-\) (or further to \(Fe^{3+}\)). Since iron loses electrons, it is oxidized.

• Option 4: Boiling of petrol

  Boiling is a physical change where liquid petrol (a mixture of hydrocarbons) turns into a gas. Similar to freezing water, this is a phase transition. While petrol can undergo combustion, which is an oxidation reaction, the act of boiling itself is not an oxidation reaction.

Oxidation Reaction Example

Based on the analysis, the rusting of iron is the only process listed that represents a chemical reaction involving oxidation, where iron loses electrons.