Question

Dehydration of hydrates of halides of calcium, barium and strontium i.e. $\left[ CaC{{l}_{2}}6{{H}_{2}}O \right],\text{ }\left[ BaC{{l}_{2}}2{{H}_{2}}O \right],\left[ \text{ }SrC{{l}_{2}}6{{H}_{2}}O \right]$ , can be achieved by heating. These become wet on keeping in the air. Which of the following statements is correct about these halides?
(A) Act as a dehydrating agent.
(B) Can absorb moisture from air.
(C) Tendency to form hydrate decreases from calcium to barium.
(D)All of the above.

Answer 1

Hint : We know that the addition of water molecules to another molecule is termed as hydration. It has many uses in organic chemistry such as the synthesis of alcohol and also in inorganic chemistry such as production of metallic hydroxides and many more.

Complete Step By Step Answer:
As we know some compounds like $CuS{{O}_{4}}5{{H}_{2}}O$ are called hydrated double salts. They retain water molecules in their crystal lattice but are not bonded with them covalently or electrovalent. Hydration on copper sulphate solid crystals converts them into this form. The water molecules escape when the double salt is dissolved in water. In other words it simply means to break or cut molecules with the help of water. The most common example is the hydrolysis of esters. Both the “R” groups can be similar or different. Upon hydrolysis, esters separate into their constituent alcohols and carboxylic acids.
Halides of calcium, barium and strontium act as dehydrating agents as they are hygroscopic in nature. They absorb moisture. Also they have a tendency to form hydrates which decrease from $C{{a}^{2+}}$ to $S{{r}^{2+}}$ due to increase in size and decrease in polarization power.
Therefore, the correct answer is option D.

Note :
Remember that the addition of water molecules at a molecular scale to any compound is said to be hydration. Adding water in any other way where the molecule is not integrated inside a molecule is not referred to as the same.