Question

Explain in brief the advantages and disadvantages of soft water and hard water

Answer 1

Advantages of Soft and Hard water.

• Soft water is used for drinking purposes
• Soft water is free from dissolved salts and has a pleasant taste
• The presence of salts in hard water makes it tasty, therefore, it is used in the preparation of beverages and wines
• Calcium (Ca) and magnesium (Mg) salts present in hard water are essential for the growth of our bones and teeth
• To check the poisoning of water in lead pipes, hard water is used. when hard water flows inside the lead pipe, some lead salts dissolved in the water to make it poisonous. calcium sulfate (CaSO₄) present in hard water forms insoluble lead sulfate (PbSO₄) in the form of a layer inside the lead pipe. it checks the lead poisoning

Disadvantages of using hard water

• The hard water cannot be used for washing clothes because it contains Ca²⁺ and Mg²⁺ ions, which react with soap (i.e, sodium stearate, C₁₇H₃₅COONa, or other sodium or potassium salt of higher fatty acids) to form scum or precipitate of Ca/Mg-stearate

$$\begin{gathered} \underset{\mathrm{sodium}\mathrm{stearate}\left(\mathrm{soap}\right)}{2{\mathrm{C}}_{17}{\mathrm{H}}_{35}{\mathrm{COO}}^{-}{\mathrm{Na}}^{+}\left(\mathrm{s}\right)}+\underset{\mathrm{From}\mathrm{hard}\mathrm{water}}{{\mathrm{M}}^{2+}}\to \underset{\mathrm{Metal}\mathrm{stearate}(\mathrm{white}\mathrm{curdy}\mathrm{ppt})}{{\left({\mathrm{C}}_{17}{\mathrm{H}}_{35}\mathrm{COO}\right)}_2\mathrm{M}\left(\mathrm{s}\right)\downarrow }+2{\mathrm{Na}}^{+} \\ \mathrm{where},\mathrm{M}=\mathrm{Ca}\mathrm{or}\mathrm{Mg} \end{gathered}$$

• However, after the precipitation of all the Ca²⁺ and Mg²⁺ ions present in the water, the water becomes soft and gives lathers with soap. Thus, lots of soap get wasted if clothes are washed with hard water. hence it is unsuitable for laundry
• Hardwater is also harmful to the boiler as the salts present in hard water get deposited in the form of scale and thus, reduce the efficiency of the boilers
• It cannot be used for domestic purposes as it spoils the utensil's luster and results in scale formation
• It is also harmful to industries like dying, printing, textiles, sugar, etc, as plenty of water is needed