Page 2 - LN

Solubility-

Solubility of a substance generally means the ability of the
substance to dissolve in water. Materials can be classified based on
their solubility in water. They are of two groups (considering solid
materials)

Soluble in water- Few substances (called solute) are
dissolved in water (act as solvent), they are said to be soluble
in water like sugar, common salt.
Insoluble in water- Some materials are not dissolved in water they are called insoluble
substances. E.g., sand, chalk powder,

For liquids, they are classified into two groups.

Miscible liquids- Liquids which mix completely, are known as miscible liquids. As for
examples lemon juice, milk, glycerin mix with water.
Immiscible liquids- Liquids which do not mix with one another are called immiscible
liquids. E.g. kerosene oil, cooking oil etc. with water.

Like solids and liquid, some gases are also soluble in water. Example- Oxygen, carbon
dioxide etc.

Density and Floatation

Density- Density of a substance is the mass per
unit volume.

3
The mass of 1 g of water with volume 1cm , has a
3
density of 1g/cm .
A substance which is denser than water sinks into
it, whereas a substance which is less dense than water, floats on it.

That is why a piece of wood, dry leaves float on water and a stone or an iron nail sinks into
water.

2