Desiccator: Device used to keep materials dry. Desiccant: Material used to keep other substances dry. Hygroscopic: Property of a substance that absorbs water from the atmosphere. Deliquescent: Property of a substance that absorbs so much water from the air that it forms a puddle of solution. Amalgam: An alloy (solid solution) of Hg with another metal. Concentrated: A lot of solute present…except in acid solutions where it also implies that the maximum amount of acid that can be dissolved is dissolved. Miscible: Solute and solvent are soluble in all portions. Saturated: The maximum amount of solute that can be dissolved is dissolved. (i.e. the same a “concentrated” concerning acids) Supersaturated: More than the maximum amount of solute that can be dissolved is dissolved. Unsaturated: Less than the maximum amount of solute that can be dissolved is dissolved.

Vapor Pressure Lowering Nonvolatile solutes reduce the ability of surface solvent molecules to escape the liquid. Therefore, vapor pressure is lowered. The amount of vapor pressure lowering depends upon the number of solute particles (a colligative property)

V.P.(sol’n) = C(solv) V.P.(solv) In one regard, the affect on the vapor pressure of the solution depends the character of the SOLUTE Nonvolatile Francios Raoult 1830-1901 Raoult’s Law V.P.(sol’n) = C(solv) V.P.(solv)

V.P.(sol’n) = C(solv) V.P.(solv) V.P. of pure solvent V. P. of the solution 1 Mole Fraction of Solvent

Calculate the vapor pressure of a solution of urea in water when 12 Calculate the vapor pressure of a solution of urea in water when 12.9 grams of urea (NH2CONH2) is dissolved in 54.0 mL of water at 25.0°C? The vapor pressure of pure water at that temp. is 23.8 mm Hg. V.P.(sol’n)= (3.00 mol/3.22mol) 23.8mm Hg = 22.2 mmHg

V.P.(sol’n) = C(solv) V.P.(solv) What would the vapor pressure of a water solution of CaCl2 be if you dissolved 28.6 grams of calcium chloride in 150.0 mL of water at room temp.? Remember WVP for water is 23.8 torr at R.T. 0.257 moles of CaCl2 V.P.(sol’n)= 21.8 mm Hg (You probably got 23.1 mm Hg…) 21.8 mm Hg = (0.9153) (23.8 mm Hg) V.P.(sol’n) = C(solv) V.P.(solv) 8.333/(8.333 + 0.771) = 0.9153 moles of water 3 x 0.257

V.P.(sol’n) = C(solv) V.P.(solv) Vapor Pressure Lowering…. SOLUTE Francios Raoult 1830-1901 Nonvolatile Non-ionizing Ionizing (modify mole fraction) Raoult’s Law V.P.(sol’n) = C(solv) V.P.(solv)