Water hardness

[Tanvir Ahmed Chowdhury]

Hardness in water is defined as the presence of multivalent cations. In other words, hardness is defined as the presence of soluble calcium and magnesium salts in the water. The presence of sulpahates, chlorides, carbonates and bi-carbonates of calcium, magnesium and ferrous salts make water hard. Due to water hardness, soaps and detergents can not creat foam easily. Rather they react with hardness creating metals and form insoluble organic salts.

For example, sodium stearate reacts with calcium as follows-
   
CaSO4+2RCOONa→ (RCOO)2Ca ↓ + Na2SO4
MgSO4+2RCOONa→ (RCOO)2Mg ↓ + Na2SO4

[shalauddin.ns]

Thanks you

[smriti.te]