Question

Which of the following is not suitable for use in desiccators to dry substance?
A.$conc.{H_2}S{O_4}$
B.$N{a_2}S{O_4}$
C.$CaC{l_2}$
D.${P_4}{O_{10}}$

Answer 1

Hint: To answer this question, you must recall desiccators and desiccants. Desiccator is a sealable container which maintains a low humid atmosphere for the preservation of moisture sensitive substances. It contains a suitable drying agent known as desiccant which helps with this process. Desiccators are mostly dehydrating agents or strong oxidizing agents.

Complete step by step answer:
Desiccators are used to protect chemicals which react with the water present in the air, that is, humidity. It is also used for cooling of heated objects as well as for the storage of dry objects that are hygroscopic and water sensitive.
Desiccants used in the desiccators are hygroscopic substances and are used to induce and sustain a state of dryness in the surroundings. Thus the desiccators can also be used to dry a partially wet compound.
We know that a desiccant is hygroscopic in nature. Of the given compounds in the question, concentrated sulphuric acid is not a hygroscopic compound whereas sodium sulphate, phosphorus pentoxide and calcium chloride are. Calcium chloride is most commonly used desiccant in laboratories.

Thus, the correct option is A.

Note:
Desiccants can also be used to remove water from solvents that are required for chemical reactions that cannot tolerate water. Common examples are reactions including Grignard’s reagent. A very commonly used desiccant in various places is silica gel which is used in packaged foods to retain their crispness and in containers, bottles, etc. to prevent microbial growth by absorbing the moisture present. Desiccants are also used widely in industries for controlling the level of water in gas streams.