Question 14 of 36 Sapting Learning macmillan learning The vapor pressure, P, of

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Question 14 of 36 Sapting Learning macmillan learning The vapor pressure, P, of a certain liquid was measured at two temperatures, T. It you were going to graphically determine the enthalpy of vaporizaton, AHvap, for this liquid, what points would you plot? The data is shown in this table Number Number T (K) P (kPa) 2253.82 5255.91 To avoid rounding errors, use three significant figures in the x values and fou significant figures in the y values point 1 Number Number NOTE: Keep the pressure units in kPa point 2 Determine the rise, run, and slope of the line formed by these points rise run slope Number Number Number What is the enthalpy of vaporization of this liquid? Number AHya J/ mol

Explanation / Answer

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

P = 3.82

ln P = ln (3.82) = 1.34025

T = 225.0

1/T = 0.00444

point 1 is:

x = 0.00444

y = 1.34025

P = 5.91

ln P = ln (5.91) = 1.77665

T = 525.0

1/T = 0.0019

point 2 is:

x = 0.0019

y = 1.77665

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rise = (y1-y2) = 1.34025 - 1.77665 = -0.4364

rise = (X1-X2) = 0.00444 - 0.0019 = 0.00254

slope = rise/run

= -0.4364/0.00254

= -171.83069

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

use

slope = - Hvap/R

= -171.83069 = -Hvap/8.314

Hvap = 1429 J/mol

Answer: 1429 J/mol

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