Question

Write the equation of chemical reaction taking place when hard water containing calcium chloride is passed through permutit.

Answer 1

Hint: Hard water contains salts of Ca and Mg carbonates, bicarbonates, etc which are removed by the permutit via ion exchanging. Permutit is a man-made zeolite with a molecular formula of $N{a_2}Ze$.

Complete step by step answer:
-First of all we will see what hard water is.
Hard water is the water which contains large mineral content and it is formed when water percolates through the deposits of limestone, gypsum or chalk which are mostly composed of calcium and magnesium carbonates, bicarbonates and sulphates. The hard water has many adverse effects and so it is softened via various methods to reduce the adversity.
-We will now see what permutit is.
Permutit is basically a manmade zeolite and a complex inorganic salt with a chemical formula of $N{a_2}A{l_2}S{i_2}{O_8}.x{H_2}O$. It can also be written as $N{a_2}Ze$. It is an orthosilicate of sodium aluminium compound, but chemically it is hydrated sodium aluminium orthosilicate. It has the capacity to exchange ions and is made up of microporous minerals which is why it is used for the removal of water hardness.
It is used for the softening of hard water and it operates according to the following reaction:
$N{a_2}Ze + C{a^{ + 2}} \to CaZe + 2N{a^ + }$
CaZe is the exhausted permutit formed by the removal of $C{a^{ + 2}}$ ions from the hard water. This is how permutit replaces $C{a^{ + 2}}$ ions by replacing them with $N{a^ + }$ ions.

Hence we can finally conclude that the equation of chemical reaction taking place when hard water containing calcium chloride is passed through permutit is:
$N{a_2}Ze + C{a^{ + 2}} \to CaZe + 2N{a^ + }$

Note: The water hardness is of two types: temporary and permanent hardness.
1) Temporary hardness: It is due to the presence of calcium and magnesium bicarbonate salts. It can be easily removed by boiling or by calcium carbonate (lime) addition in the process of lime softening.
2) Permanent hardness: It is due to the presence of calcium and magnesium sulphates and chlorides. It cannot be removed via boiling and so ion exchange columns or water softeners are used for removing it.