Tag: hard and soft water

Soft water is surface water that contains low concentrations of ions and in particular is low in ions of calcium and magnesium. Because soft water has few calcium ions, there is no inhibition of the action of soaps and no soap scum is formed in normal washing. It lathers easily with water. Similarly, soft water produces no calcium deposits in water heating systems.

An easy way in which water manifests its hardness is scaling i.e. forming deposits through calcification that clog plumbing. These scales are usually white because calcium and magnesium are the most common sources of hardness in water. In swimming pools, a cloudy or milky appearance characterizes hard water.

Hardness of water can be of two types temporary and permanent hardness. Permanent hard water contains chlorides and sulphates of calcium and magnesium. It can be removed by adding washing soda.

Soap is the sodium and potassium salt of organic fatty acid. Soap reacts with hard water forming scum. They are derived from the treatment of tryglycerides with a strong base (saponification). Soaps are made by rendering fats from animal sources.

Detergents are soap-like compounds which are used for cleaning purpose. They are sodium salts of long chain alkyl benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphate, whereas, soaps are sodium salts of long chain carboxylic acids.

Permanent hard water can be made soft by adding sodium carbonate (also called washing soda) to it. This will soften both temporal and permanent hardness. In this chemical reaction, the calcium and magnesium ions react with sodium to form a precipitate.

Water which gives lather with soap easily is called as soft water.

Calgon is a trade name of a complex salt, sodium hexametaphosphate $(NaPO _3) _6$.