you are provide with a mixture of nepthalene and sodium chloride. Suggest an activity to separate them with the help of labeled diagram.
Answers
The mixture of naphthalene and sodium chloride can be separated by the process of sublimation as naphthalene is a sublime, i.e. it turns into vapour without changing in liquid and its vapour change into solid without changing into liquid, while sodium chloride is not a sublime.
Activity:
Materials required: China glass, funnel, tripod, gas burner, spatula, cotton.
Process:
Take the mixture in a china glass.
Put it on the tripod.
Cover the mixture with a funnel by putting it inverted on the china glass.
Plug the tip of the funnel using some cotton.
Now start heating the china glass containing mixture.
Stop heating after 30 to 60 second when vapour starts rising in the funnel.
Leave the apparatus to get cooled.
You will observe that naphthalene gets deposited on the inner wall of the funnel because of sublimation leaving the sodium chloride in the china glass.
Scratch out the naphthalene deposited on the inner wall of the funnel.
Naphthalene is insoluble in water but soluble in benzene (organic solvent). Ammonium chloride is soluble in water but insoluble in benzene. Naphthalene changes into vapours at room temperature whereas ammonium chloride changes into vapours on heating.
Method
(a) Add water to the mixture and shake it vigorously to dissolve ammonium chloride.
(b) Filter the mixture. Naphthalene is obtained as residue whereas, filtrate contains ammonium chloride. Crystallise the filtrate by heating till saturated solution of ammonium chloride is obtained.