Lecture 7 – Separating a mixture of 2 solids out of which one sublimes

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Figure	Source of Figure
Figure 10	www.meritnation.com

Technique 7: Separating a mixture of 2 solids out of which one sublimes

A mixture of 2 solids out of which one sublimes can be separated using the apparatus shown in Figure 10.

Figure 10: 

Consider a mixture of solid Iodine and sand. The apparatus consists of a China dish containing the mixture. A funnel is inverted and placed on the dish. The nozzle of the funnel is sealed using cotton plug to ensure that no vapours leave the apparatus.  The mixture is heated in the apparatus shown. Heat causes Iodine to sublime. The sublimed Iodine vapours leave the mixture and rise upwards. On reaching the walls of the inverted funnel, the iodine vapours condense to form solid iodine which clings to the walls of the funnel. Hence, the mixture is separated into its constituent materials.

The cotton plug prevents the escaping of iodine vapours to the surroundings.