Question

In the laboratory during preparation of hydrogen gas mention the changes that would occur also write the chemical reaction for the following changes.
(a) in place of zinc granules same amount of zinc Dust in is taken in test tube.
(b) instead of dilute sulphuric acid hydrochloric acid is taken.
(c) in place of zinc copper turning are taken.
(d) Sodium Hydroxide is taken in place of sulphuric acid and the

Answer 1

a) If the zinc granules have been replaced by the zinc dust to react with sulfuric acid, then the reaction will take place faster and so, the Hydrogen gas will be developed at a faster rate.

This is because of the boost in the surface area which in turn increases the reaction rate.

b). If hydrochloric acid is used in place of Sulphuric acid, then the products formed will be hydrogen gas and zinc chloride instead of zinc sulphate. There will be no change in the reaction rate.

 Zn + 2HCl → ZnCl₂ + H₂O

c). Copper is less reactive than zinc when it has to respond with dilute acids. This is because copper is a noble metal and it lies in the lower reactivity series. So if the zinc granules are replaced with copper turnings, then no reaction will occur and so hydrogen gas will not be produced.

 d). If Sodium hydroxide is taken, then hydrogen gas and sodium zincate will be formed. If this mixture is heated, then hydrogen gas will be developed at a faster rate as heating increases the rate of reaction.

 Zn + 2NaOH → Na₂ZnO₂ + H