[bottleofboos]

The vapor pressure of an unknown liquid was measure as described in this experiment:
At 1.7 Celsius, vapor pressure is 9.8 mm Hg.
At 21.2 Celsius, vapor pressure is 35.2 mm Hg.
At 44.8 Celsius, vapor pressure is 158.0 mm Hg.

I had to draw the Graph of ln Vapor Pressure vs. 1/T

a. Determine the molar heat of vaporization:
Slope = delta ln(Vapor Pressure)/delta(1/Temperature)= - delta H vaporization/R
R = 8.31 J/mol K

I got the slope = -5679.1 and heat of vaporization = 47193.7 J/mol.

b. If the barometric pressure of the lab was approximately 760 mm Hg, find the normal boiling point of the liquid. (Calculate T in Celsius)

I got:
1/T= -1.1x10³
T= -878.0 K = -1151.2 C

What did I do wrong?