Question

Why should impure zinc be used instead of pure zinc in preparation of hydrogen gas​

Answer 1

Pure zinc is not used for the preparation of hydrogen gas because it is non-porous. As a result, the reaction carried out with pure zinc would be too slow. Hence impurities like copper is often added to the zinc. Copper acts as a catalyst ( by providing a large surface area ) and increases the speed of the reaction.

Answer 2

Explanation:

Pure zinc is not used for preparation of hydrogen gas because it is non-porous. As a result, the reaction carried out with pure zinc would be too slow. Hence, impurities like copper is often added to the zinc. Copper acts as a catalyst and increases the speed of the reaction.