Third Law of Thermodynamics
Third Law of Thermodynamics: Overview
This topic teaches the third law of thermodynamics. It explains how this law helps in measuring the entropies at different temperatures. It also discusses the conditions of the molecules in the solid state.
Important Questions on Third Law of Thermodynamics
Identify the correct statement regarding entropy:

The for the reaction at when
respectively is

The standard entropies of and are . The value of of formation of ammonia is

What is residual entropy of the substance?

Calculate the entropy change for the following reaction at and pressure.
, the absolute entropy values () for and .

Write the statement of third law of thermodynamics.

Third law of thermodynamics helps in the calculation of the absolute entropy of a substance at any temperature ‘’.

The third law of thermodynamics states that, the entropy of a perfect crystal at a temperature of zero degree Celsius is equal to zero.

State the third law of thermodynamics.

Why is it impossible for any substance to have an absolute entropy zero at temperature greater than ?

State third law of thermodynamics. What is its usefulness?

Which of the following allotropes of sulphur has maximum at ?

Among the following, the reaction that is accompanied by a decrease in the entropy is

The true statement amongst the following is

The correct statement regarding entropy is:

Identify the correct statement regarding entropy.

Entropy is a measure of disorder. For perfect crystalline substances at , entropy becomes:

For a perfectly crystalline solid Cp,m = aT3 , where 'a' is constant. If Cp,m is at 10 K, molar entropy at 20 K is :

Which law of thermodynamics help in calculating entropy at different temperatures?

The entropy of a perfectly crystalline material is zero at . This statement matches with the-
