카이스트 소재열역학의 이해 기말고사 족보.docx

Final Exam
MS212, Spring Term 2xxx
Prof. WooChul Jung
June 21, 2xxx

1. (20 points) Answer the following short questions.

a) When is true Identify a specific state variable that needs to be constant for it.

b) Explain why Cp is always higher than Cv for ideal gas.

c) At constant composition, does Gibbs free energy increase or decrease with increasing temperature

increase decrease

d) In a particular solid solution of A and B atoms with composition 50% A and 50% B, the probability that a particular bond is A-A (as opposed to A-B or B-B), is 0.4. This state has a given configurational entropy of mixing S0. In order to make the entropy increase, should I increase it, decrease it or is the system entropy already maximal

increase decrease S is already maximal

2. (20 points) N2 gas follows van der Walls equation with a=1.39 L2atm/mol2 and b=0.0391 L/mol. Calculate ΔG and ΔS when one mole of N2 gas expands from 1 L to 2 L at 400 K.

…

3. (20 points) MgCl2 (A) and MgF2 (B) forms solution in particular range of compositions. The Gibbs free energy of fusion of MgF2 and the Gibbs free energy of mixing of liquid MgCl2 and MgF2 can be represented as follows.

a) Plot the Gibbs free energy of mixing of this system as a function of composition of MgF2 at 1173K.

b) Explain how to get the solubility of MgF2 in liquid MgCl2 at 1173 K. MgCl2 does not dissolve in solid MgF2.

4. (20 points) Phase diagram of a mixture is shown below. Draw ΔGM of the liquid solution (L) and the solid solution (S) in terms of xB at the given temperature ranges.

a) Tm, A`T`Tm, B

b) T`TC

5. (20 p