The vapor pressure, P, of a certain liquid was measured at two temperatures, I.

Question

The vapor pressure, P, of a certain liquid was measured at two temperatures, I. If you were going to graphically determine the enthalp vaporizaton, AHvap, for this liquid, what points would you plot? The data is shown in this table Number Number T(K)P (kPa) 2753.56 575 5.3 To avoid rounding errors, use three significant figures in the x values and four significant tigures in the y values point 1:.004 1.269 Number Number NOTE: Keep the pressure units in kPa point 2: .001 1.669 Determine the rise, run, and slope of the line formed by these points rise run slope Number Number Number .4 0.003 133.3 at is the enthalpy of vaporization of this liquid? Number J/ mol vap1108.53

Explanation / Answer

We need to plot lnK on y axis and 1/T on x axis

P = 3.56

ln P = ln (3.56) = 1.26976

T = 275.0

1/T = 0.00364

point 1 is:

x = 0.00364

y = 1.26976

P = 5.31

ln P = ln (5.31) = 1.66959

T = 575.0

1/T = 0.00174

point 2 is:

x = 0.00174

y = 1.66959

----------------------------------------------------------------------------

rise = (y1-y2) = 1.26976 - 1.66959 = -0.39983

rise = (X1-X2) = 0.00364 - 0.00174 = 0.0019

slope = rise/run

= -0.39983/0.0019

= -210.74441

----------------------------------------------------------------------------

use

slope = - Hvap/R

= -210.74441 = -Hvap/8.314

Hvap = 1752.129 J/mol

Answer: 1752 J/mol

Feel free to comment below if you have any doubts or if this answer do not work. I will edit it if you let me know

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