Question

Zeolite used to soften hardness of water is, hydrated:
A.Potassium aluminium borate
B.Sodium aluminium silicate
C.Calcium aluminium borate
D.Zinc aluminium borate

Answer 1

Hint: We must remember that the zeolite layer in which zeolite is regenerated by passing a brine solution. The soft water layer will be above this zeolite layer which is free from impurities. Calcium and magnesium zeolites settle at bottom.

Complete answer:
We know that within the permutit process salts which cause hardness of water are replaced by salts of sodium. We have to remember that the zeolites contain aluminates and silicates which have the capability to attract cations. In the permutit process, hardened water is softened by using sodium zeolites. Zeolites are complex inorganic salts like hydrated sodium aluminium silicates. Sodium aluminium silicates have a molecular formula as \[N{a_2}A{l_2}S{i_2}{O_8}\], which is used to soften hardness of water.
The sodium zeolite reacts with salts of magnesium and calcium which converts them to magnesium and calcium zeolites. After sometime sodium zeolite is completely converted to calcium and magnesium zeolites so reactions stop. Then, 10% brine solution is passing through these calcium and magnesium salts which regenerate back sodium permutit which we can reuse to softening of hard water.
In this reaction as there’s no precipitate formation, hard water has no obstruction to return into the chamber. It is a quick process and may be easily managed.
Therefore, the sodium aluminium zeolite is used to soften the hardness of water.
Option A, C and D: In these options borates are not used to remove hardness of water. So, these features are wrong.
Therefore, the solution to this present question is option B that is Sodium aluminium silicate.

Note:
We can listed out the other methods for the softening the hardness of water are,
-Lime softening: In this process lime is added to the hard water to make it softer.
-Chelating agents are water softeners which are used in commercial products like shampoo and food preservatives.
-In the washing soda method, chlorides and sulphates of calcium and magnesium convert into their carbonates as precipitate.