A few crystals of ferrous sulphate were taken in a dry boiling tube and heated. Tiny water droplets were…
A few crystals of ferrous sulphate were taken in a dry boiling tube and heated. Tiny water droplets were observed in the tube after some time.
(i) From where did these water droplets appear ? Explain.
(ii) What colour change will be observed during heating ?
(iii) How many molecules of water are attached per molecule of FeSO4 crystal ? Write the molecular formula of crystalline forms of (I) Copper sulphate, and (II) Sodium carbonate.
(iv) State how is Plaster of Paris obtained from gypsum. Write two uses of Plaster of Paris.
Solution
(a)
(i) The molecules of water of crystallisation in ferrous sulphate crystals get evaporated on heating.
(ii) Green → White
(iii) Seven / (FeSO4·7H2O)
(I) CuSO4·5H2O
(II) Na2CO3·10H2O
(iv) On heating gypsum (CaSO4·2H2O) at 373 K it loses water molecules/ CaSO4·2H2O $\xrightarrow{\text{373K}}$ CaSO4·½H2O + 1½H2O
Two uses of Plaster of Paris:
Making toys / material for decoration
Supporting fractured bones (or any other)