Question

In comparison to the zeolite process for the removal of permanent hardness, the synthetic resins method is

• A. More efficient as it can exchange only cations
• B. Less efficient as the resins cannot be regenerated
• C. More efficient as it can exchange both cations as well as anions
• D. Less efficient as it exchanges only anions.

Answer 1

Answer: (C)

(A) Zeolite method removes only cations ( $Ca^{2 +}$ and $Mg^{2 +}$ ion) present in hard water
$2NaZ+M^{2 +}\left(\right.aq\left.\right) \rightarrow MZ_{2}\left(\right.s\left.\right)+2Na+\left(\right.aq\left.\right)\left(\right.M \rightarrow Mg,Ca\left.\right)$
(B) Synthetic resin method removes cations ( $Ca^{2 +}$ and $Mg^{2 +}$ ion) and anions (like $Cl^{-},HCO_{3}^{-},SO_{4}^{2 -}$ etc.)