Question

Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method.

(a) Salt from sea water

(b)Ammonium chloride from sand

(c)Chalk powder from water

(d)Iron from sulphur

(e)Water and alcohol

(f)Sodium chloride and potassium nitrate

(g)Calcium carbonate and sodium chloride.

Answer 1

(a) The technique used to separate the salt from seawater is Evaporation.
Reason – Because this method is used to separate the components of the homogeneous solid-liquid
mixture. In this method, sea water is collected in a shallow bed and allowed to evaporate in the sun.
When all the water is evaporated, salt is left behind. By this method, we only get solid and liquid is
evaporated in its vapour form.
(b) Technique used to separate Ammonium chloride from sand is sublimation.
Because this method is used for solid mixtures in which one of the components can sublime on
heating. In this method, Ammonium chloride changes into vapours on heating and salt is left behind.
(c) Technique used to separate chalk powder from water is ltration.
Reason – Because this process is used to separate the components of a heterogeneous solid-liquid
mixture in which solids are lights and insoluble in liquids. Substances used as lters are sand lter
paper at C. These lters allows the liquid to pass through them, but not solids.
(d) Technique to separate iron from sulpher is magnetic separation.
Because, this method is used when one of the component of mixture is Iron. Iron gets attractedtowards the magnet and hence get separated.
(e) Technique used to separate water and Alcohol is Fractional Distillation.
Because in this method, the vapours of water is left behind in the original vessel as the alcohol boils at
lower temperature than water. Thus these two liquids can be separated.
(f) Technique used is Fractional-crystallisation.
Because: This method is used when solubility of solid components of mixture and different in the
same solvent. Here, sodium chloride and potassium nitrate. Both are soluble in water but solubility of
potassium nitrate is more.
(g) Technique used is Solvent Extraction Method: Because, by this method, salts get dissolve in water
while calcium carbonate being insoluble in water settles down in the container. And hence get
separated about.