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

ID: 844193 • Letter: T

Question

The vapor pressure, P, of a certain liquid was measured at two temperatures, T. The data is shown in this table.

T(K) P(kPa)

325 3.28

775 7.10

If you were going to graphically determine the enthalpy of vaporizaton, ?Hvap, for this liquid, what points would you plot?

x y

point 1 x axis in 3 significant figures and y axis in 4 significant figures _____ _______

pont 2 x axis in 3 significant figures and y axis in 4 significant figures _____ _______

Determine the rise, run, and slope of the line formed by these points.

rise _______________ run ________________ slope ______________

What is the enthalpy of vaporization of this liquid?

_________________ J/mol

Let T(K) be x and P(kPa) your y

Point 1: x1= 1/325= .00307, y1=ln(3.28)= 1.187
Point 2: x2= 1/775= .00129, y2=ln(7.10)= 1.960

Rise= y2-y1= 1.960-1.187= .773
Run= x2-x1= .00129-.00307= -.00178
Slope= y2-y1/x2-x1= .773/-.00178= -434.26

deltaHvap= mxR= 434.26x8.314= 3610.437 J/mol
(R is a constant)

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