Question

How would you prepare:

zinc sulphate crystals from zinc dust (powdered zinc and zinc oxide).

Answer 1

Take dilute sulphuric acid in a beaker and heat it on wire gauze. Add some granulated zinc pieces with constant stirring. Add till the Zinc settles at the base of the beaker. Effervescences take place because of liberation of hydrogen gas. When effervescence stops, it indicates that all the acid has been used up. The excess of zinc is filtered off. Collect the solution in china dish and evaporate the solution to get crystals. Filter, wash them with water and dry them between the folds of paper. The white needle crystals are of hydrated Zinc sulphate.

\[\ce{Zn_{(s)} + H2SO4_{( aq)}-> ZnSO4 + H2\uparrow}\]

\[\ce{ZnO + H2SO4 -> ZnSO4 + H2O}\]

\[\ce{ZnSO4 + 7H2O -> \underset{White vitriol}{ZnSO4.7H2O}}\]