Table of Contents
Definition:
Temporary and Permanent hardness of the water. The nature of water which does not easily produce foam with soap but produces foam after consuming enough soap is called water hardness or hardness. Bicarbonate salts like calcium (Ca), magnesium (Mg), aluminum (Al), ferrous iron (Fe), sulfate, and chloride salts like chloride, etc. are dissolved in water. Chemical reactions with these salts produce insoluble soaps that do not foam with water. As a result, soap is wasted.
Aluminum (AI), Ferrous Iron (Fe), and the presence of sodium (Na), potassium (K), and ammonium (NH) salts in water do not cause harshness. Because soap is the sodium or potassium salt of organic acid. So soap does not react with sodium, potassium, and ammonium salts.
Names of salts that cause hardness in water:
Bicarbonate salts: calcium bicarbonate, magnesium bicarbonate, ferrous bicarbonate.
Chloride Salts: Calcium Chloride, Magnesium Chloride, Aluminum Chloride.
Sulfate salts: calcium sulfate, magnesium sulfate, aluminum sulfate
Classification of Hardness
There are two types of water hardness. E.g.
1. Temporary Hardness
2. Permanent Hardness
1. Temporary and Permanent hardness of water-Temporary Hardness:
The hardness of water when bicarbonate of calcium, magnesium, and ferrous iron is dissolved in water is called temporary hardness of the water. Temporary hard water is called temporary hard water. The reason why this hardness is called temporary is that it is removed by simple methods such as the water boiling method.
2. Temporary and Permanent hardness of water-Permanent Hardness:
The hardness of water as a result of dissolving chlorides and sulfate of calcium, magnesium, and aluminum in water is called permanent hardness. Permanent hard water is called permanent hard water. Permanent hardness cannot be eliminated by any simple method.
Causes of soap wastage in hard water:
Soap is the sodium salt of stearic acid, which dissolves in water and produces foam. And removes the dirt from the foam fabric generated. Like calcium, magnesium, aluminum, and ferrous salts are present in hard water, they react with sodium stearate (soap) to produce soluble precipitates of insoluble calcium, magnesium, etc.
The resulting precipitates are separate from the water as a kind of lubricating substance. As a result, soap decays but no foam is produced. Thus salt cannot produce foam until the salts of calcium, magnesium, etc., have become insoluble precipitates. As a result, soap is wasted.
Source of Hardness in Natural Water:
During rain, when rainwater begins to reach the surface through the atmosphere, the air reacts with carbon dioxide to produce carbonic acid. The crustal soil contains chalk, limestone, magnesium carbonate, ferrous carbonate, etc. When rainwater flows over the earth’s crust or flows downstream, carbonic acid reacts with the earth’s limestone or chalk, calcium carbonate, etc., to convert them into soluble bicarbonate. Gypsum
is mined in the soil and is slightly soluble. So if there is gypsum in the soil and rainwater flows over it, it dissolves some amount of gypsum and mixes with the water. In many places, calcium chloride, magnesium sulfate, magnesium chloride, etc. are soluble in the soil. Therefore, they are dissolved in the water of ponds, rivers, canals, seas, etc.
