# lec8 - Last Time Solubility Enthalpy of solution Lattice...

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1 Last Time • Solubility • Enthalpy of solution • Lattice Enthalpy • Hydration Enthalpy • Single Ion Enthalpy – careful • Colligative Properties Machinery – Concentration • Molality m = moles of solute/mass of solvent • Mole Fraction X c = moles of component/total moles • Mass percentage composition = mass of component/total mass x 100 Example Given that the mole fraction of calcium chloride in 100 g of water is 0.01, calculate the molality of the solution and the mass percent composition of both water and calcium chloride. Who Cares? • Mole fraction – vapor pressure lowering – Raoult’s Law P = X solvent x P pure • Molality – T f depression Δ T f = –ik f x m

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2 Example By how much does the vapor pressure at room temperature and freezing point of 1 L of water change by adding 100 mg of NaCl? K f = 1.86 K kg/mol Δ H vap = 40.7 kJ/mol Uses • Practical heat transfer • Estimation of mass and molecular weight • Understand multicomponent liquid mixtures
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## This note was uploaded on 03/18/2012 for the course CHEM 2B taught by Professor Clemens during the Winter '08 term at UC Davis.

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lec8 - Last Time Solubility Enthalpy of solution Lattice...

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