Question

When zeolite is treated with hard water, the sodium ions are exchanged with:

• A. $H^{+}$
• B. $C{a}^{2+}$
• C. $O{H}^{-}$
• D. $S{O}_4^{2-}$

Answer 1

The correct option is B $C{a}^{2+}$

Zeolites are used to remove the hardness of water. They are used to remove $C{a}^{2+}$ ions from water which is responsible for the hardness. When zeolite is treated with hard water, the $N{a}^{+}$ ions are exchanged with $C{a}^{2+}$ ions.

$N{a}_{2}Z\left(s\right)+C{a}_{aq}^{2+}\to CaZ\left(s\right)+2N{a}^{+}\left(aq\right)$