21-VPressure-Prob-Ans

21-VPressure-Prob-Ans - VAPOR PRESSURE AND HEAT OF...

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VAPOR PRESSURE AND HEAT OF VAPORIZATION ( Hvap) GCHEM II LAB CONCEPT PROBLEMS Raoult’s Law: Vp Total = P P(A) + P P(B) + P P(N) Pp (A) = [mole fraction (A) ] * [Vp (Pure A) ] Hvap (kJ/mole) = Heat required to vaporize one mole of liquid at a temperature Graphical Calculation to Calculate Heat of Vaporization: [y = m x + b] [lnP = ( Hvap) x 1/T + b] m = slope = ( Hvap) Hvap = –( slope) x R R R Clausius Claperon to Calculate Heat of Vaporization: ln (P 2 /P 1 ) = ( Hvap /R) (1/T 1 – 1/T 2 ) where: R=8.31 x10 -3 (kJoules/moles-K) and T(K) 1. A solution of 78.4 grams of benzene (C 6 H 6 ) and 92.4 grams of toluene (C 7 H 8 ) is placed in a container open to the atmosphere at 20.0 o C. If the vapor pressure of pure benzene is 75.5 torr and pure toluene is 22.6 torr, what is the partial pressure of the benzene over the solution ? what is total pressure ? 78.4 grs benzene 1 mole benzene = 1.0037 mole benzene mole fraction = 1.0037/1.0037 + 1.0029 = .5002 78.108
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This note was uploaded on 07/28/2011 for the course CHM 2046c taught by Professor Staff during the Summer '08 term at UNF.

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21-VPressure-Prob-Ans - VAPOR PRESSURE AND HEAT OF...

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