Question

In the following schematic diagram for the preparation of hydrogen gas as shown in the figure, what would happen if 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 sulphuric 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. Hydrogen gas would evolve at a greater speed because zinc dust provides more surface area as compared to zinc granules.
2. Both would react in the same way. There would be no effect on the volume of the gas evolved.
3. Copper does not react with either dilute HCl or dilute H₂SO₄. No gas would evolve in both the cases.
4. Hydrogen gas would evolve in this case also.
   `"Zn" + 2"NaOH" overset("heat")(->) underset("Sod. zincate")("Na"_2"ZnO"_2) + "H"_2`