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

ID: 865071 • Letter: T

Question

The vapor pressure, P, of a certain liquid was measured at two temperatures, T. The data is shown in this table. If you were going to graphically determine the enthalpy of vaporizaton, deltaHvap, for this liquid, what points would you plot? To avoid rounding errors, use three significant figures in the x values and four significant figures in the y values. NOTE: Keep the pressure units in kPa. Determine the rise, run, and slope of the line formed by these points. What is the enthalpy of vaporization of this liquid?

Explanation / Answer

Background

According to Clausius-Clapeyron equation:

ln P = -dHvap/(RT) + const

It means a linear relation (y=ax+b) between lnP and 1/T.

The slope is