Question

Boiling hard water with washing soda removes permanent hardness.
A) True
B) False

Answer 1

Permanent hardness of hard water is due to the presence of calcium sulfate/calcium chloride and/or magnesium sulfate/magnesium chloride in the water.

Complete step by step answer:
First of all, let's understand about soft and hard water. Water that produces lather with soap readily is called soft water. Water which does not produce lather with soap readily is called hard water. Hardness of water is due to the presence of bicarbonate, chloride, sulphate of calcium and magnesium in it. The process of removing hardness i.e. soluble bicarbonates, chlorides and sulphates of calcium and magnesium from hard water is called softening of water. There are various methods of softening of hard water but in this question, we are going to discuss whether washing soda removes the permanent hardness of the hard water. Washing soda is an inorganic compound with molecular formula ${\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$. It has the molecular mass of ${\text{106 g}}$. Washing soda is a chemical compound that can be used to remove the tough stains in laundry and is an essential component in most homemade laundry detergent. Washing soda is also used to remove the permanent hardness of the hard water. During the process of removal of hardness from the hard water, hard water is treated with a calculated amount of washing soda ${\text{(N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}})$. When impurities of chlorides and sulphate of calcium and magnesium are present in hard water that reacts with washing soda, impurities get precipitated as insoluble calcium and magnesium carbonate which can be easily filtered off. The water thus becomes soft.
${\text{CaC}}{{\text{l}}_{\text{2}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} \to {\text{CaC}}{{\text{O}}_{\text{3}}}{\text{ + 2NaCl}}$
${\text{MgS}}{{\text{O}}_{\text{4}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} \to {\text{MgC}}{{\text{O}}_{\text{3}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}$
Moreover, temporary hardness of hard water can also be removed by using Washing soda. So we got to know that Washing soda can be used to remove both temporary and permanent hardness of water.

Note:
Hard water should not be confused with heavy water. Both of them are different things. Heavy water is deuterium oxide i.e. ${{\text{D}}_{\text{2}}}{\text{O}}$. whereas we discussed hard water in the above format.