Question

\(2 \mathrm{KClO}_{3}+\mathrm{I}_{2} \rightarrow 2 \mathrm{~K} 1 \mathrm{O}_{3}+\mathrm{Cl}_{2}\) Which of the following statements is correct regarding the above reaction? (1) It is a simple displaccment but not a redox reaction (2) Chlorine is reduced by iodine (3) Chlorinc is oxidiscd by iodine (4) It is a metathesis reaction

Short answer

Option (2) is correct: Chlorine is reduced by iodine.

Step-by-step solution

Identify Oxidation States

Determine the oxidation states of each element in the reactants and products:

Oxidation States in Reactants

For \(\mathrm{KClO_{3}}\): K is +1, Cl is +5, and O is -2. For \(\mathrm{I_{2}}\): I is 0.

Oxidation States in Products

For \(\mathrm{KIIO_{3}}\): K is +1, I is +5, and O is -2. For \(\mathrm{Cl_{2}}\): Cl is 0.

Determine Changes in Oxidation States

Compare the oxidation states in the reactants and the products. Cl changes from +5 to 0: reduction. I changes from 0 to +5: oxidation.

Identify the Correct Statement

The correct statement is: 'Chlorine is reduced by iodine.' which corresponds to option (2).

Key concepts

oxidation states

An oxidation state, also known as an oxidation number, is a concept that helps us understand how many electrons an atom gains or loses during a chemical reaction. It’s a number assigned to an element in a compound, representing its real or hypothetical charge. For example, in \(\text{KClO}_3\), potassium (K) has an oxidation state of +1, chlorine (Cl) has +5, and oxygen (O) has -2.

To figure out oxidation states:

• Free elements, like \(\text{I}_2\), have an oxidation state of 0.
• For monoatomic ions, it's the same as the ion's charge.
• In compounds, sum of oxidation states should equal the compound’s overall charge.

Knowing the oxidation states is key to identifying which elements are oxidized or reduced in a reaction.

reduction

Reduction is a process where an atom gains electrons, lowering its oxidation state. Think of it as the atom becoming more 'negative' in charge. In the reaction \(2\text{KClO}_3 + \text{I}_2 \rightarrow 2\text{KIIO}_3 + \text{Cl}_2\), chlorine’s oxidation state changes from +5 in \(\text{KClO}_3\) to 0 in \(\text{Cl}_2\). That means chlorine gains electrons, which means it's reduced.

Here’s a simple way to remember:

• Reduction involves Gain of Electrons (OIL RIG: Reduction Is Gain).
• Reduction leads to a decrease in oxidation state.

oxidation

Oxidation is the opposite of reduction. It happens when an atom loses electrons, increasing its oxidation state. In our example reaction, iodine starts with an oxidation state of 0 in \(\text{I}_2\) and ends up with +5 in \(\text{KIIO}_3\). This increase shows that iodine loses electrons, thus it's oxidized.

This is how you can tell:

• Oxidation involves Loss of Electrons (OIL RIG: Oxidation Is Loss).
• Oxidation leads to an increase in oxidation state.