Problem Set #27: Understanding Phase Diagrams

University:
The Pennsylvania State University
Course:
CHEM 450 | Thermodynamics
Academic year:

2024
Views:

111

Pages:

2
Author:

Alexis H.

Problem Set #27 Assigned: March 11, 2024 Due: March 13, 2024 at 2:30 pm 1. Consider the phase diagram shown below. Invoke the concept of chemical potential to explain the presence of the lines separating the various phases. For example, what is the relationship between the chemical potential of the solid and the liquid along the phase coexistence line? What is the relationship of the chemical potential for the three phases at the triple point? Next, consider the liquid region. How does the chemical potential of the liquid phase compare to that of the solid and the gas phases within the liquid region? The chemical potential between the phases is zero when something is declared in one phase or the other. If something is a solid then it’s chemical potential for liquid would be zero. If it’s on. boundary line then it has equal potential for both two separate phases and at the triple point it has equal potential for all three phases. 2. Why does the distinction between the liquid and vapor phases disappear above the critical point? 3. Consider the phase diagrams shown below. l (a) How many phases are present at each point a – d on the left diagram? (b) How many phases are present at each point a – d on the right diagram? (a) a - 1 b-2 c-2 d-2 (b) a - 1 b-2 c-3 d-2 2. Above the critical point there is no clear distinction between the gas and liquid phase because molecules have too much kinetic energy to be held together by intermolecular forces