HW #5, WB.1 - Pxy Diagram and Henry's Law Constants for Dichloromethane and Methanol - 14 pts

VLE data for the system dichloromethane(1) and methanol(2) at 50oC appear in the table below.

a.) Make a Pxy Diagram in Excel based on this data. No curve fit is necessary. Describe any unusual features in this diagram. Be specific and quantitative in your description.
b.) Make a fugacity or partial pressure plot (plot y1 P vs x1 and y2 P vs x1 on the same figure) in Excel. SVN Figure 12.2 is an example of such a plot.
c.) Determine the Henry's Law Constant at 50oC for each species from the partial pressure curves constructed in part b. Draw a line on each graph from part b, by hand or using Excel's drawing tools, that shows the graphical interpretation of the Henry's Law Constant for each species. (Ans.: Low-tech method (use last 2 data points and draw a line): k2 = 334 kPa/(mole 2/mol), High-tech method (fit the last 3 data points to a quadratic eqn and determine the slope as xi approaches 0): k2 = 437 kPa/(mole 2/mol) )
d.) Estimate the range of x1 values over which H1 is applicable and the range of x2 values over which H2 is applicable. Consider H values applicable as long as the error incurred is less than 5% of the partial pressure of the species.

Data :

P (kPa) x1 y1
55.55 0.000 0.000
58.79 0.042 0.093
61.76 0.097 0.174
64.59 0.189 0.265
65.66 0.292 0.324
65.76 0.349 0.349
65.59 0.415 0.367
65.15 0.493 0.386
63.86 0.632 0.418
62.36 0.720 0.438
59.03 0.835 0.484
54.92 0.893 0.537
48.41 0.945 0.620
31.10 1.000 1.000