Question

How can a mixture of sand, potassium chloride, and iodine be separated?

Answer 1

Hint: Potassium chloride having formula $KCl$ has the property of sublimation i.e., on heating the substance will directly convert from solid to gas. Iodine can be dissolved in water and then heat the solution to get iodine.

Complete step by step answer:
So we are given a mixture of three compounds: sand, potassium chloride, and iodine. These can be separated one by one as follows:
Take the mixture as a china dish and heat the mixture on the Bunsen burner. Now the potassium chloride having formula $KCl$ has the property of sublimation i.e., on heating the solid potassium chloride will directly convert into gas form. So when we heat the mixture, cover the china dish with a funnel. Due to heating the $KCl$ will convert into gas and stick to the funnel. When the heating is stopped, remove the funnel and cool it for a few minutes, the solid $KCl$ can be obtained.
Now we are left with sand and iodine in the mixture and we know that the sand is not soluble in water but the iodine is soluble in water. So this mixture is dissolved in water and then filtered. The sand will filter out and the solution will contain iodine and water. This solution can be heated from which the water will evaporate and the iodine will be left. So, all three components get separated.

Note: When the mixture is heated first, it should be heated at around ${{770}^{\circ }}C$ because it is the melting point of potassium chloride. The sand will not melt at this temperature because the melting point of sand is ${{1700}^{\circ }}C$.