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

Question

Mapu The vapor pressure, P, of a certain liquid was measured at two temperatures, If 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) 275 3.70 825 8.21 To avoid rounding point 1 errors, use three significant figures in the x values and four significant figures in the y values Number Number NOTE: Keep the pressure units in kPa. point 2 Determine the rise, run, and slope of the line formed by these points. ise run slope Number Number Number What is the enthalpy of vaporization of this liquid? Number J/ mol Exit O Previous ) Give Up & View Solution 0 Check Answer 0 Next Hint

Explanation / Answer

ans)

Here We need to plot lnP on y axis and 1/T on x axis
P = 3.70
ln P = ln (3.70) = 1.31
T = 275 K
1/T = 1/275 = 0.003636

point 1 is:
x = 0.003636
y = 1.31

P = 8.21
ln P = ln (8.21) = 2.105
T =825 K
1/T = 1/825 = 0.001212

point 2 is:
x = 0.001212
y = 2.105

rise = (y1-y2) = (1.31 - 2.105) = -0.795
run = (x1-x2) = (0.003636 - 0.001212) = 0.002424

slope = rise/run
= -0.795/0.002424
= - 327.97
use:
slope = - delta Ho/R
-327.97 = - delta Ho / 8.314
delta Ho = 2727 J/mol

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