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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: XGen on August 22, 2012, 05:38:41 PM

Title: Enthalpy/Entropy of Vaporization
Post by: XGen on August 22, 2012, 05:38:41 PM
Arsine, AsH3, is a highly toxic compound used in the electronics industry for the production of semiconductors. Its vapor pressure is 35 Torr at -111.95 degrees Celsius, and  253 Torr at -83.6 degrees Celsius. Using these data, calculate (a) the standard enthalpy of vaporization; (b) the standard entropy of vaporization; (c) the standard Gibbs free energy of vaporization; (d) the normal boiling point of arsine.

For part A, I thought should be a simple "plug and chug" involving the Clausius-Clapeyron equation. My expression was ln (253/35) = (ΔH/8.314)(1/161.05 - 1/189.4), which evaluates to about 17.7 kJ/mol. However, this does not match the answer in my textbook.

I do not really know how to approach part B at all. The other two parts seem to flow from these first two parts.