Question

Which of the following can be separated by using a separating funnel and which cannot be separated by using a separating funnel?
(i) water and kerosene mixture
(ii) water and acetone mixture
(Give reasons for your answer.

Which method is better for recovering sugar from sugar solution: evaporation or crystallisation? Give reason for your answer.

Answer 1

(i) Water and kerosene can be separated by using separating funnel as there is a difference in their densities due to which they can be easily separated. There is a difference in their colour also, so they can be easily separated.

(ii) Water and acetone mix together and form homogenous solution, so it is not possible to separate them using separating funnel.

Crystallization is a solid-liquid separation technique in which the solute transformed from the liquid state to the solid state. The solid state is obtained in the pure crystallization form. As compared to evaporation, it is considered as a better method to obtain sugar from sugar solution because:
1. The sugar will be obtained in pure crystalline form. In case of evaporation, impurities would be present.
2. When we obtain sugar from water, it may be possible that along with water molecules, sugar molecules may also be lost as the sugar may decompose on heating.