Liquids expand with the rise in temperature just like solids. The solids have definite shapes. Hence, in the case of solids, three types of expansion (linear, surface, and volume) are significant. But liquids have no definite shape. Thus unlike solids, liquid expansion with the change in temperature is studied only in terms of the change in volume.
Characteristics Features in Thermal Expansion of Liquids:
1. For the same rise in temperature, the thermal expansion of a liquid is about ten times that of a solid of the same volume.
2. For the same rise in temperature, different liquids of equal volume expand differently.
3. The rate of thermal expansion differs a little for the different ranges of temperature change.
Types of Thermal Expansion of Liquid:
Apparent Expansion of Liquid:
The expansion of a liquid, ignoring the expansion of the container is called the apparent expansion of the liquid.
Coefficient of Apparent Expansion of Liquid:
The apparent expansion of the unit volume of a liquid for a temperature rise of 1° is called the Coefficient of Apparent Expansion of Liquid.
γ’ = apparent expansion / initial volume x rise in temperature
Note: The coefficient of apparent expansion of a liquid isn’t an intrinsic property of the liquid. It depends on the material of the container. Hence a liquid may have different values of γ’ when heated in containers of different materials.
Real Expansion of Liquid:
The sum of the apparent expansion of the liquid and the expansion of the container is called the real expansion of the liquid.
Coefficient of Real Expansion of Liquid:
The actual or real increase of unit volume of a liquid for a temperature rise of 1° is called the Coefficient of Real Expansion of Liquid.
γ = real expansion / initial volume x rise in temperature
Note: The coefficient of real expansion is an intrinsic property of the liquid and doesn’t depend on the material of the container.