Tfp 20.16

P [bar]

x_R134a

0.84

0.0397

2.12

0.1086

3.95

0.1956

6.15

0.2904

9.71

0.4272

13.2

0.5508

17.32

0.6867

19.56

0.777

20.16

0.8075

20.64

0.8427

20.75

0.8572

1) [20 pts] The gas solubility of 1,1,1,3-tetrafluoroethane (R-134a) in the ionic liquid 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide ([HMIm][Tf2N] (the same system from HW#2) at 70°C is given to the right (Ren & Scurto, Fluid Phase Equil. 2009). As the ionic liquid has no measurable dew point, the vapor phase is considered pure. Determine the Henry’s Constant and the appropriate composition range (i.e. linear):

a) Assuming an ideal gas mixture vapor phase

b) Assuming the Peng-Robinson EoS is valid for R-134a

Note: to use the PR EoS program from the disk you need to add R-134a into the database that the software accesses for the properties. Go to the Microsoft Access database file (pure_prop.mdb) and insert the last row of the following (copy/paste) as a new compound at the end of the list. The folder and file should be in your “Program Files” folder.

pure_property

No

Formula

Name

Molwt

Tfp

Tb

Tc

Pc

Vc

Zc

Omega

Dipm

CpA

CpB

CpC

CpD

619

C2H2F4

1,1,1,2-tetrafluoroethane

102.03

169.85

246.8

374.3

40.6

0.3268

26.28055

0.19466667

0.000061693

-0.0000001877

(Technically only the Tc, Pc, and omega are needed for this HW)

2) [20 pts] 11.2-22

3) [40 pts] For the system Benzene (1) and CS2 (2), the 1-constant Margules expression adequately models the data due to the symmetry of activity coefficients. For data at a 50/50 mixture by mole, the GEX is equal to 290 J/mol at 25°C; and the HEX is = 525 J/mol (temperature independent). The melting point of benzene is 5.5°C (fusH=9.9 kJ/mol) and for CS2 is -108.6°C (fusH=4.39 kJ/mol).

a) [15 pts] Determine the Solid-Liquid Equilibrium across the composition/temperature range and plot

b) [15 pts] Determine if an upper consolute temperature (upper critical point) exists for this system. Be sure to show all stability requirements.

c) [10 pts] At 46.5°C, the vapor pressure of CS2 is 1.013 and for benzene 0.320 bar. Does a azeotrope form at this temperature?

4) [20 pts] 11.3-8: (use van Laar)

Optional Problems (not graded, but suggested):

1) 11.1-2 2) 11.2-9