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

Question

The vapor pressure, P , of a certain liquid was measured at two temperatures, T. DATA T(K) P(K Pa) 225 3.12 625 7.52 Graphically determine the enthalpy of vaporization. For this liquid what points would you plot? Round 3 sig figs for x values, and 4 sig figs for y values. (x,y)Point 1 :(X) number (Y) number (x,y)Point 2 :(X) number (Y) number Then determine the rise, run, and slope if line formed by these points. rise= run= slope= What is the enthalpy of vaporization of this liquid? = _________J/mol PLEASE SHOW WORK STEP BY STEP ***************************************************************************************************************** So far this is what i did X1=1/225=.00444*** X2=1/625=.0016 I know Y1=In(3.12) i dont know what (IN) is please help i'm confused because i don't know what to mutiple 3.12 and 7.52 with to get Y1 and Y2.

Explanation / Answer

Using Clausius-Clapeyron Equation:
ln (p1/p2) = (deltaHvap / R)(1/T2 - 1/T1)
you just plug in the values that you have for p1, p2, T1, and T2 where R= 8.3145 J mol-1 K-1
so: ln (8.59/4) = (delta H /8.314)(1/775 - 1/325)
(0.764)(8.314) = delta H(-450/251875)
SO THAT delta H = 3556.71 J/mol = 35.56 KJ/mol

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