CHEM 1061 Lecture Notes - Lecture 25: Molar Mass, Triple Point, Vaporization
Document Summary
Liquid vapor: endothermic, - hvap, pesolid < peliquid. Heat of vaporization: heat in k needed to vaporize 1 mol of liquid at 1atm. H bonds in liquid = increased heat of vaporization. Equilibrium: point where no further net change can be seen because evaporization rate and condensation rate are equal. Equilibrium vapor pressure: pressure of the vapor at equilibrium. Sublimation: a phase change directly from solid to gas, skipping the liquid phase. Rate of evaporization remains constant while the rate of condensation increases as the number of molecules in the gas phase increases until the two rates equal. Vaporization is a function of intermolecular forces: as forces increase, vapor pressure decreases, as molar mass increases, vapor pressure decreases. Equations: ln(pvap) = (- hvap/r)(1/t)+c, ln((pvap 1, t1)/(pvap 2 , t2) = ( hvap/r)((1/t2)-(1/t1)) Heating curve: plot of temperature vs time where energy added is constant. Heat of fusion ( hfus): enthalpy change at the melting point: hvap> hfus.
