Chemistry
How would you prepare zinc sulphate crystals from zinc dust (powdered zinc and zinc oxide).
Answer
Zinc sulphate crystals from Zinc dust
Method of preparation: Displacement — By the action of dilute acid (dil. H2SO4) on an active metal (Zinc, Iron).
Reaction:
Zn(s) + H2SO4(aq) ⟶ ZnSO4 + H2↑
ZnSO4 + 7H2O ⟶ ZnSO4.7H2O (white vitriol)
Procedure:
- Take dilute sulphuric acid in a beaker and heat it on a wire gauze. Add some granulated zinc pieces with constant stirring.
- Effervescence take place because of the liberation of hydrogen gas.
Add zinc till the Zinc settles at the base of the beaker.
When effervescence stops, it indicates that all the acid has been used up. - The excess of zinc is filtered off.
- Collect the solution in a china dish and evaporate the solution to get crystals. Filter, wash them with water and dry them between the folds of a filter paper. The white, needle-shaped crystals are of hydrated Zinc sulphate.
Related Questions
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(a) Direct combination
(b) Displacement
(c) Double decomposition (precipitation)
(d) Neutralization of insoluble base
(e) Neutralization of an alkali (titration)
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