Question

Cation and anion exchange resins are used in the ion-exchange process. (State whether true or false.)
A. True
B. False

Answer 1

Ion exchange is actually a reversible chemical reaction in which dissolved ions are basically removed from the solution and are replaced with the other ions having the same or similar electrical charge.

Complete answer:
Ion-exchange resin serves as a physical medium which facilitates the ion exchange reactions. The ion-exchange resin is mainly composed of the organic polymers (for example: polystyrene) which form a network of hydrocarbons. Ion exchange sites are present throughout the polymer matrix where functional groups having either positively-charged cations or negatively-charged anions are present on the polymer network. Now, these functional groups easily attract the ions of opposite charges.
For instance, in case of cation exchange resin, sodium ions get exchanged by the calcium and magnesium ions from the hard water. Thus, this process helps in the softening of water. Let us have a look on the zeolites alumino-silicate polymer having exchangeable sodium ions:
$2NaAlS{i_2}{O_6} + C{a^{2 + }} \longrightarrow Ca{\left( {AlS{i_2}{O_6}} \right)_2} + 2N{a^ + }$
The above chemical equation indicates that the hardness is removed through ion-exchange resin.
Similarly, anion exchange resins exchanges negative ions and thus, possess the exchangeable anions such as $C{l^ - },{\text{ }}S{O_4}^{2 - },O{H^ - }$. These are often styrene–divinylbenzene copolymer resins having the quaternary ammonium cations as an integral part of resin matrix.
$N{R_4}^ + O{H^ - }\; + {\text{ }}HCl \longrightarrow N{R_4}^ + C{l^ - }\; + {\text{ }}{H_2}O$
Anion-exchange resins are generally used to extract and purify the materials from either mixtures or solutions.
Hence, the given statement is true. Cation and anion exchange resins are used in the ion-exchange process.

**Thus, the correct answer is Option A.

Note:**
The ion-exchange resin matrix is actually formed by the cross-linking of hydrocarbon chains with one another through polymerization. The cross-linking provides strength to the resin polymer and more resilient structure with a greater capacity. The resin polymer undergoes further chemical treatments to bind the functional groups at the ion exchange sites which are located throughout the matrix.