In Clark's process for removing hardness of water, the reagent used is

Options

A. Acidic
B. Basic
C. Neutral
D. Both (1) & (2)

Answer

**Step-by-Step Solution:**

1. **Understanding Hardness of Water:**
Hardness in water is primarily due to the presence of dissolved minerals, mainly calcium (Ca²⁺) and magnesium (Mg²⁺) ions. There are two types of hardness: temporary and permanent. Temporary hardness is mainly due to bicarbonates of calcium and magnesium.

2. **Clark's Process:**
Clark's process is a method used to remove temporary hardness from water. It involves the addition of a reagent that reacts with the calcium and magnesium ions to form insoluble precipitates.

3. **Reagent Used:**
In Clark's process, the reagent used is slaked lime, which is chemically represented as calcium hydroxide (Ca(OH)₂). When slaked lime is added to hard water, it reacts with the bicarbonate ions (HCO₃⁻) present in the water.

4. **Chemical Reaction:**
The reaction can be represented as follows:
\[ Ca(OH)_2 + Ca(HCO_3)_2 \rightarrow 2CaCO_3 (s) + 2H_2O \]
Here, calcium carbonate (CaCO₃) precipitates out of the solution, thus removing the hardness.

5. **Conclusion:**
Therefore, the reagent used in Clark's process for removing hardness of water is slaked lime (calcium hydroxide).

**Final Answer:**
The reagent used in Clark's process for removing hardness of water is slaked lime (calcium hydroxide).

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