By doing some simple calculations and plotting several graphs, one can verify some of the statements made in this chapter concerning phase equilibrium and phase transitions. All the calculations should be done using the steam tables. 

a. Establish, by direct calculation, that

for steam at 2.5 MPa and T = 224°C. 

b. Calculate G^V at P = 2.5 MPa for a collection of temperatures between 225 and 400°C and extrapolate this curve below 224°C. 

c. Find G^L at 160, 170, 180, 190, 200, and 210°C. Plot this result on the same graph as used for part (b) and extrapolate above 224°C.  For a liquid H and S can be taken to be independent of pressure. Therefore, the values of H and S for the liquid at any pressure can be gotten from the data for the saturated liquid at the same temperature. How does this graph compare with Fig. 7.3-7?

Fig. 7.3-7

d. Plot V versus T at P = 2.5 MPa for the temperature range of 150 to 400°C, and show that V is discontinuous. 

e. Plot C_P versus T at P = 2.5 MPa over the temperature range of 150 to 400°C, and thereby establish that C_P is discontinuous.

f. Using the data in the steam tables, show that the Gibbs energies per unit mass of steam and liquid water in equilibrium at 300°C are equal. 

Transcribed Image Text:

GL = GV