Test: Entropy - 1 - Mechanical Engineering MCQ

 at the peak of the entropy hill. 

Thus, total entropy change for the process B is smaller and therefore it is less irreversible.

The system undergoes an internally reversible, isothermal process, and thus its entropy change, 

TdS= dH - VdP
TdS = C_p dT - VdP
TdS - C_p d T - 0
(for constant pressure process)

∴  

(for constant volume process)
∴  

S = K ln W  
where, S is entropy
K is Boltzmann constant
W is thermodynamic probability
when W = 1, it represents the greatest order,
S = 0. This occurs only at T = 0 K. This is the Nernst-Simon statement of third law of themnodyanamics.

The entropy of the system (the sum of the entropies of the water and ice) must increase when the ice is melted in the water. This is because energy must be introduced to the system in the form of heat to break the bonds between the molecules of ice, increasing the entropy of the system.