Question

Vacuum desiccator is used……
A. For drying crystals
B. For purifying crystals
C. For separation of crystals
D.For the process of crystallization

Answer 1

Hint: There exist two different types of compounds that can absorb water from the atmosphere at room temperature and they are hygroscopic and deliquescent compounds. One major difference between the two is that the former does not form a solution while absorbing moisture where the latter absorbs water to the extent that a solution is obtained. These substances that remove moisture from the environment are known as desiccants.

Complete step by step answer:
A Desiccator is usually a bowl of thick glass with a lid, there exists a perforated ceramic disc that separates it into two partitions, the drying agent i.e., desiccator is placed beneath the silica disc and the chemical that needs to be dried or keep at dry condition is placed above the disc. As we know the desiccators are hygroscopic compounds that keep the atmosphere dry by absorbing the moisture in the air, the chemical in the desiccator gets the dry conditions. The common chemicals that can be used as desiccators are calcium sulphate (\[CaS{O_4}\]) also known as Drierite, silica gel, etc. The compound generally stored in desiccators is cobalt chloride paper to prevent it from absorbing moisture from the atmosphere.
Hence the correct answer is option A.

Note: Common Desiccants used are Drierite (\[CaS{O_4}\]), silica gel, ${P_2}{O_5}$, \[MgS{O_4}\]. Out of these drierite is commonly used desiccants. Also, the desiccants are not only used for absorbing moisture but also for other purposes such as activated charcoal that have the dual behaviour of not only absorbing the moisture but also eliminates odour and activated alumina is used as desiccators and also a filter of fluoride and arsenic from drinking water.