Calculate the vapor pressure of heptane (b.p. 98.0 °C) at the gas chromatography

Question

Calculate the vapor pressure of heptane (b.p. 98.0 °C) at the gas chromatography column temperature of 88.0 °C using the form of the Clausius-Clapeyron equation, where R is the ideal gas constant, Hvap is the enthalpy of vaporization, T1 and T2 are two different temperatures, and P1 and P2 are the vapor pressures at the respective temperatures. The enthalpy of vaporization can be estimated using Trouton's rule, H°vap = (88 J mol–1 K–1)·Tbp.

Calculate the vapor pressure of hexane (b.p. 69.0 °C) at the same column temperature.

I just need help with this bold part.

Explanation / Answer

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ln(P2/P1) = dH/R*(1/T1-1/T2)

subtitute known data

normal P = 1 atm, T1 = 69°C; P2 0 ? T2 = 98°C

ln(P2/1) = 34.7*1000/8.314*(1/(69+273)-1/(98+273))

solve for P2

P2 = exp( 34.7*1000/8.314*(1/(69+273)-1/(98+273))) =

P2 = 2.5958 atm

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