Equilibria of HN3: Find Vapor Pressure, Enthalpy & Entropy

Thread starter physicsss
Start date Apr 6, 2005
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To determine the standard enthalpy of vaporization, standard entropy of vaporization, and standard free energy of vaporization for HN3, the vapor pressures at -22.75 C and 25 C are essential. The standard enthalpy of vaporization can be calculated using the Clausius-Clapeyron equation, while the standard entropy of vaporization can be derived from the enthalpy values. For the standard free energy of vaporization, the equation ln(P) = -G/(RT) is relevant, where P is the vapor pressure in Torr, R is the ideal gas constant (8.3145 J/(mol·K)), and T is the temperature in Kelvin. The appropriate vapor pressure to use corresponds to the temperature of interest, and the temperature should be converted to Kelvin for calculations. The relationship G = H - TS can also be applied to find the free energy, incorporating the previously calculated enthalpy and entropy values.

Apr 6, 2005

physicsss

The vapor pressure of HN3 is 58 Torr at -22.75 C and 512 Torr at 25C. Find the standard enthalpy of vaporization, standard entropy of vaporization, the standard free energy of vaporization.

I know how to find the first two, but for some reason I can't find the third one...Is the equation for it lnP=-G/(RT). If so, what unit is P in and which P should I use and is R 8.3145 and what temperature do I use?

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Apr 7, 2005

gravenewworld

did you try G=H-TS?

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