can sublimation be used as a separation technique? explain with the help of a suitable diagram
Answers
SEPARATION OF TWO SOLIDS BY THE METHOD OF SUBLIMATION - DEFINITION
If a mixture of two solids contain a solid which can sublime on heating then sublimation is used. The mixture is heated and the solid which sublimes is collected in inverted flask and is scratched out. e.g. ammonium chloride and iron.
SUBLIMATION - DEFINITION
Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.
EXPERIMENT
Ammonium chloride changes directly from solid gaseous on heating . So to separate mixtures containing a sublimable volatile component from a non-sublimable impurity i.e., sodium chloride, the sublimation process is used.
• Place the china dish over a wire gauze placed over a tripod stand.
• Cover the china dish with an inverted glass funnel and plug in a little cotton at the opening stem.
• On heating the mixture, white fumes evolve.
• Stop heating when the fumes stop rising and allow the funnel to cool.
• On cooling, remove the funnel and transfer the solid ammonium chloride sticking on the walls of funnel to a watch glass.
