WATER

– It is a universal solvent and maintains the body temperature due to its high specific heat.

– Its density is maximum at  4°C.

– 22nd March is  World Water Day.

– Density of ice is lower than that of water. That's why it floats over water.

TYPES OF WATER

Soft Water

– Soft Water easily lather with soap.

Hard Water

– It does not lather with soap. It is of two types

1. Temporary Hard Water It contains bicarbonate of calcium and magnesium. It is converted into soft water by boiling or by adding calculated quantity of calcium hydroxide. (Clarke's process).

2. Permanent Hard Water It contains sulphates and chlorides of calcium and magnesium. It is converted into soft water by adding sodium carbonate (Na2Co3) or calgon or zeolite. Calgon is sodium hexametaphosphate, Na2[Na4(Po3)6]. Permutit or zeolite is  hydrated sodium aluminium silicate.