Question

Assertion: ${\rm{CaC}}{{\rm{l}}_{\rm{2}}}$ can’t be used for drying ethyl alcohol
Reason: Calcium chloride can form an addition compound with ethyl alcohol
A. Both Assertion and Reason are true and Reason is the correct explanation to Assertion
B. Both Assertion and Reason are true and Reason is not the correct explanation to Assertion
C. Assertion is true and Reason is false
D. Assertion is false but Reason is true

Answer 1

We know that, ethanol is the chemical compound which chemical formula is ${{\rm{C}}_{\rm{2}}}{{\rm{H}}_{\rm{5}}}{\rm{OH}}$.The functional group present in the compound is alcohol (-OH). The functional groups are the atoms or groups of atoms that decide the chemical properties of the compound.

Complete step by step answer:
Let’s first understand the drying agent. They are anhydrous salt (inorganic) that absorbs water of hydration on exposure to wet solution or moist air. Some commonly used drying agents in laboratory are sodium sulphate $\left( {{\rm{N}}{{\rm{a}}_{\rm{2}}}{\rm{S}}{{\rm{O}}_{\rm{4}}}} \right)$, calcium chloride $\left( {{\rm{CaC}}{{\rm{l}}_{\rm{2}}}} \right)$ etc. in their anhydrous form.

Now, we have to understand whether the drying of ethanol is possible by calcium chloride or not. We know that alcohols such as methanol and ethanol react with calcium chloride to form alcoholates of calcium, that is, an additional compound. The formula of the addition compound is ${\rm{CaC}}{{\rm{l}}_{\rm{2}}}.4{{\rm{C}}_{\rm{2}}}{{\rm{H}}_{\rm{5}}}{\rm{OH}}$. So, we can say that calcium chloride forms an additional compound on reaction with ethanol and thus it cannot be used for drying alcohol.

Therefore, both the assertion and reason is correct and reason explains the assertion.

So, the correct answer is Option A.

Note:
The differences between drying agents and dehydrating agents are:

Drying agents	Dehydrating agents
1)They do the work of removal of moisture from other substances	1)They do the work of removal of water molecules that are chemically combined from other substances
2)They do not undergo reaction chemically	2)They undergo chemical reaction with other substances
3)Example: Anhydrous Calcium chloride , dry sodium sulphate etc.	3)Example: Sulphuric acid (Conc.)

Always remember that an ideal drying agent is the one that does not undergo reaction with the substance that needs to be dried. Calcium chloride cannot be used for drying alcohol but it can be used as a drying agent for other inorganic molecules. Generally alcohols dehydrate using the method of distillation.