Postlab 3 - Name: Jeff Johnson Quiz Section: BJ DATA,...

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Unformatted text preview: Name: Jeff Johnson Quiz Section: BJ DATA, CALCULATIONS AND GRAPHS Pentane Temperature, K 1/Temperature, K VP, mmHg VP, atm Ln (VP, atm) 0.3 273.45 3.66E-03 219.67 2.89E-01-1.2412 4.0 277.15 3.61E-03 240 3.16E-01-1.1527 6.1 279.25 3.58E-03 259.26 3.41E-01-1.0755 8.6 281.75 3.55E-03 280.55 3.69E-01-0.9966 10.7 283.85 3.52E-03 300.55 3.95E-01-0.9277 12.7 285.85 3.50E-03 322.26 4.24E-01-0.8580 14.3 287.45 3.48E-03 340.57 4.48E-01-0.8027 15.9 289.05 3.46E-03 360.57 4.74E-01-0.7456 17.4 290.55 3.44E-03 380.55 5.01E-01-0.6917 18.9 292.05 3.42E-03 400.59 5.27E-01-0.6404 20.5 293.65 3.41E-03 421.87 5.55E-01-0.5886 21.7 294.85 3.39E-03 441.03 5.80E-01-0.5442 23.0 296.15 3.38E-03 459.76 6.05E-01-0.5026 24.0 297.15 3.37E-03 478.49 6.30E-01-0.4627 25.0 298.15 3.35E-03 493.38 6.49E-01-0.4320 26.0 299.15 3.34E-03 512.54 6.74E-01-0.3939 27.1 300.25 3.33E-03 531.27 6.99E-01-0.3580 28.2 301.35 3.32E-03 552.98 7.28E-01-0.3180 30.1 303.25 3.30E-03 590.01 7.76E-01-0.2532 31.1 304.25 3.29E-03 612.57 8.06E-01-0.2157 31.9 305.05 3.28E-03 631.73 8.31E-01-0.1849 2 pts Temperature, o C EXPERIMENT 3: INTERMOLECULAR FORCES Part II: VAPOR PRESSURE THE ENTHALPY OF VAPORIZATION PURPOSE The purpose is to measure the enthalpies of vaporazation of pentane, diethyl ether, 2-butanone, and 2-butanol. How is the enthalpy of vaporization measured? (3 pts) We collect a range of temperature and vapor pressure readings. We plot ln(vapor pressure) vs 1/temperature (because the relashionship is nonlinear). This comes out as a line with slope equal to -deltaH / R. For each of these molecules, a portion of the enthalpy of vaporization is ascribed to dispersion forces (all molecules have dispersion forces) and a polar component. Which molecule provides the dispersion forces component for itself and all the others and what assumption is made in order to use the value for one compound to account for the dispersion forces in all the others? (2 pt) The deltaH measured for n-pentane is used to approximate the dispersion component of the other molecules. This works as long as the other molecules are roughly the same in all other respects: they have about the same molar mass and polorizability, so they're assumed to have similar dispersion forces....
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This note was uploaded on 05/08/2008 for the course CHEM 162 taught by Professor N. during the Spring '08 term at University of Washington.

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Postlab 3 - Name: Jeff Johnson Quiz Section: BJ DATA,...

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