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

(a) Salt from sea water is separated by evaporation method. Evaporation method is used to separate the components of a homogeneous solid-liquid mixture. The liquid is escaped in the form of vapour and the solid is left behind.

(b) Sublimation method is used to separate ammonium chloride from sand. This method is used when one of the component is sublime in nature. Ammonium chloride is sublime in nature so when it is heated, ammonium chloride directly changes into vapours and sand is left behind. The vapours of ammonium chloride on cooling changes directly into solid.

(c) Chalk powder and water can be separated by filtration method. Filtration method is used for separating insoluble solids from liquids. On filtration, chalk powder gets deposited on filter paper whereas water passes through the filter paper and gets collected in the beaker.

(d) Iron from sulphur can be separated by magnetic separation method. This method is used when one of the component is magnetic in nature. Iron gets attracted towards magnet and can easily be separated from sulphur.

(e) Water and alcohol can be separated by fractional distillation method using a fractionating column fitted over the distilling flask. Fractional distillation method is used to separate miscible mixtures in which the liquids have different boiling points. Boiling point of alcohol is 78°C and water is 100°C. Hence, this method is the most suitable for separating them. 95.5% pure alcohol is obtained by this method.

(f) Sodium chloride and potassium nitrate can be separated by fractional crystallization. This method is used when the solubility of solid components of a mixture is different in the same solvent. Both salts are soluble in water but solubility of potassium nitrate is more than that of sodium chloride in water.

(g) Solvent extraction method is used to separate calcium carbonate and sodium chloride mixture. This method is used when one component is soluble in a particular liquid while the other component is insoluble. Sodium chloride is soluble in water but calcium carbonate is insoluble which settles down.