In preparation of hydrogen, zinc granules are preferred over pure zinc because they

Options

A. are easily available
B. reduce hydrogen
C. contain copper as impurity
D. act with HCI

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question asks why zinc granules are preferred over pure zinc in the preparation of hydrogen gas. To answer this, we need to consider the properties and reactions of zinc when it interacts with hydrochloric acid (HCl).

2. **Reaction of Zinc with HCl**: When zinc (Zn) reacts with hydrochloric acid (HCl), it produces zinc chloride (ZnCl₂) and hydrogen gas (H₂). The chemical equation for this reaction is:
\[ \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

3. **Zinc Granules vs. Pure Zinc**: Zinc granules are small pieces of zinc, while pure zinc refers to zinc in its elemental form without any impurities. The question implies that there is a specific reason for choosing zinc granules over pure zinc.

4. **Presence of Impurities**: Zinc granules often contain impurities, such as copper. The presence of these impurities can significantly affect the reaction. In this case, copper acts as a catalyst.

5. **Role of Copper as a Catalyst**: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. The copper impurity in zinc granules speeds up the reaction between zinc and HCl, leading to a more efficient production of hydrogen gas.

6. **Conclusion**: Therefore, zinc granules are preferred over pure zinc for the preparation of hydrogen because the copper impurity acts as a catalyst, enhancing the reaction rate.

**Final Answer**: Zinc granules are preferred over pure zinc in the preparation of hydrogen because they contain copper as an impurity, which acts as a catalyst and speeds up the reaction with hydrochloric acid.

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