Question

Explain the experiment of measuring the real and apparent expansion of a liquid with a neat diagram.

Answer 1

1. To start with, the liquid whose real and apparent expansion is to be determined is poured into a container up to a level. Mark this level as L₁.
2. Now, heat the container and the liquid using a burner as shown in the figure Initially, the container receives the thermal energy and it expands.
3. As a result, the volume of the liquid appears to have reduced. Mark this reduced level of liquid as L₂.

Element	No. of Protons	No. of Neutrons	Mass Number	Stable Isotopes (abundance)	Atomic Mass (amu)
Nitrogen	7	7	14	N - 14 (99.6%)	14.004
	7	8	15	N - 15 (0.4%)
Silicon	14	14	28	Si - 28 (92.2%)	26.04
	14	15	29	Si - 29 (4.7%)
	14	16	30	Si - 30 (3.1%)
Chlorine	17	18	35	CI - 35 (75%)	35.5
	17	20	37	CI - 37 (25%)

On further heating, the thermal energy supplied to the liquid through the container results in the expansion of the liquid. Hence, the level of liquid rises to L₃. Now, the difference between the levels L₁ and L₃ is called apparent expansion, and the difference between the levels L₂ and L₃ is called real expansion. The real expansion is always more than that of apparent expansion.
Real expansion = L₃ – L₂
Apparent expansion = L₃ – L₁.