Question

Question 43.
In the following schematic diagram for the preparation of hydrogen gas as shown in the figure, what would happen if the following changes are made?

1. In place of zinc granules, same amount of zinc dust is taken in the test tube.
2. Instead of dilute acid, dilute hydrochloric acid is taken.
3. In place of zinc, copper turnings are taken.
4. Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

Answer 1

1. If the same amount of zinc dust is taken in the test tube then the reaction will be comparatively faster and hydrogen gas will evolve with greater speed. It is because zinc dust has a larger surface area than zinc granules.
2. With dilute hydrochloric acid, almost the same amount of gas is evolved.
3. With copper turnings, hydrogen gas will not evolve because copper is less reactive, so, it does not react with dil. ${\text{H}}_2{\text{SO}}_4$ of dil. HCl. Hence, no reaction will take place.
4. Zinc also reacts with NaOH. So, if sodium hydroxide is taken, then hydrogen gas will be evolved.

$\text{Zn}+2\text{NaOH}\to {\text{Na}}_2\text{Zn}{\text{O}}_2+{\text{H}}_2$