Dicuss briefly de- mineralistion of water by ion exchange resin.

Explanation

### Step-by-Step Solution for Demineralization of Water by Ion Exchange Resin

1. **Definition of Demineralized Water**:
- Demineralized water is water that is free from any cation or anion impurities. It is important to understand that this type of water does not contain dissolved salts, which are typically found in hard water.

2. **Understanding Hard and Soft Water**:
- Hard water contains impurities in the form of cations (e.g., calcium ions, magnesium ions) and anions (e.g., sulfate ions, bicarbonate ions). In contrast, soft water has fewer dissolved minerals.

3. **Ion Exchange Resin**:
- Ion exchange resins are materials that can exchange specific ions within the resin with ions in a solution. There are two types of ion exchange resins: cation exchange resins and anion exchange resins.

4. **Cation Exchange Process**:
- In the first step, cation exchange occurs. The cation exchange resin (denoted as R) interacts with the cation impurities (denoted as M⁺).
- The reaction can be represented as:
\[ R^+ + M^+ \rightarrow R^+M + H^+ \]
- Here, the cation impurity (M⁺) is exchanged with the hydrogen ion (H⁺) from the resin, effectively removing the cation impurity from the water.

5. **Anion Exchange Process**:
- The second step involves anion exchange. The anion exchange resin (denoted as RnH₂) interacts with the anion impurities (denoted as X⁻).
- The reaction can be represented as:
\[ RnH_2 + OH^- \rightarrow RnH_3^+ + OH^- \]
- The anion impurity (X⁻) is exchanged with hydroxide ions (OH⁻) from the resin.

6. **Formation of Demineralized Water**:
- After the cation and anion exchange processes, the solution contains H⁺ and OH⁻ ions. These ions react to form water:
\[ H^+ + OH^- \rightarrow H_2O \]
- The final product is demineralized water, which is free of any cation or anion impurities.

7. **Conclusion**:
- The process of demineralization using ion exchange resins effectively removes all dissolved salts from water, resulting in pure water that is suitable for various applications.