A student was asked by his teacher to separate an impure sample of sulphur containing sand as the impurity. He tried to purify it with the help of sublimation. But he was not successful. Particles of sulphur of sulphur could not be separated completely from sand.
(i) Why did the sublimation process succeed ?
(ii) Suggest an alternate method to affect the separation.
(iii) What is the value based information associated with this ?

Explanation

(i) Sulphur is not of volatile nature. Upon heating it melts. Therefore, sublimation process could not succeed.
(ii) The student should have dissolved the impure sample in carbon disulphide. It is a liquid in which sulphur completely dissolves while iron does not. From the solution, can be recovered with the help of crystallization process.
(iii) The process of sublimation is useful only if one of the constituents present in the mixture can sublime while the others do not undergo sublimation.