lecture 9 - Turn on Camptasia Recording No Class Monday Feb...

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Unformatted text preview: Turn on Camptasia Recording! No Class Monday Feb 18th PRESIDENT's DAY Class will be held Tuesday Feb 19th No Class Wednesday Feb 20th EXAM WED Feb 20th 131 Markus at 7 pm due to EXAM ... 1 SI Sessions Sunday Feb 17th, NONE Due to Holiday Wednesday Feb 20th NONE Due to Exam Review Sessions Tuesday Feb 19th 5:30 pm (Hardy) GOESSMAN 51 Tuesday Feb 19th 5:30 pm (Tami) TBA ... 2 The enthalpy of solution for NaOH is: A.Negative B.Positive BP ii ... 3 Before Tiffany opened the selzer water, the CO2 concentration was 0.0506 M (at 25C). What was the pressure of CO2 gas in the bottle in mm Hg? Gas solubility (in mol/L) = kH Pgas kH for CO2 = 4.48 x 10-5 M / mmHg ... 4 Effect of Temperature on Solubility of a Gas: For all gases solubility with temperature This is due to Le Chatlier's Principle 5 ... Today's take home messages! Vapor Pressure Lowering Boiling Point Elevation Freezing Point Depression ... 6 Understanding Colligative Properties VP of H2O over a solution depends on the number of H2O molecules per solute molecule. Psolvent proportional to Xsolvent ... 7 Vapor Pressure Lowering ... Figure 14.14 8 Raoult's Law Assume a solution containing 10 0 g 10.0 sucrose (C12H22O11) in 40.0 g of water. What is the vapor pressure of water over the solution at 80C? (The VP of pure H2O is 355.1 mm Hg; see App. G.) ... 9 Raoult's Law With 2-components where A is the solvent and B 2is the solute VP lowering is proportional to mol frac solute! solute! For very dilute solutions, where K is a proportionality constant. constant. This helps explain changes in melting and boiling points. ... 10 Changes in Freezing and Boiling Points of Solvent VP Pure solvent 1 atm P VP solvent after adding solute BP solution T ... 11 BP pure solvent Boiling Point Changes The boiling point of a solution is higher than that of the pure solvent. ... 12 Boiling Point Elevation VP Pure solvent 1 atm P VP solvent after adding solute BP solution T ... 13 BP pure solvent Change in Boiling Point If we dissolve 62.1 g of glycol (1.00 mol) in 250. g of water. What is the BP of the solution? KBP = +0.512 oC/molal for water ... 14 Change in Freezing Point Pure water Ethylene glycol/water solution The freezing point of a solution is LOWER than that of the pure solvent. solvent. ... 15 Lowering the Freezing Point Water with and without antifreeze When a solution freezes, the solid phase is pure water. The solution becomes more concentrated. ... 16 Freezing Point Depression Calculate the freezing point of a 4.00 molal glycol/water solution. Kfp = -1.86 oC/molal p ... 17 Boiling Point Elevations and Freezing Point Depressions with ions i = van't Hoff factor = number of particles produced per formula unit. Compound Ethylene glycol NaCl CaCl2 Theoretical Value of i 1 2 3 ... 18 Freezing Point Depression Q: How much NaCl must be dissolved in 4.00 kg of water to lower the freezing point to -10.00 oC? (Kfp = -1.86 oC/molal) ... 19 Osmosis Solvent S l t Solution Semipermeable membrane The semipermeable membrane allows only the movement of solvent molecules. Solvent molecules move from pure solvent to S l l l f l solution in an attempt to make both have the same concentration of solute. Driving force is entropy ... 20 Osmosis ... 21 Osmosis at the Particulate Level ... 22 Osmotic Pressure, Equilibrium is reached when pressure produced by extra solution counterbalances pressure of solvent molecules moving through the membrane. OSMOTIC PRESSURE, = cRT (c is conc. in mol/L) Osmotic pressure ... 23 Osmosis Osmosis of solvent from one solution to another can continue until the solutions are they have the same concentration. ISOTONIC -- ... 24 Osmosis and Living Cells No water in or out Water goes out of cell ... Water goes into cell 25 Reverse Osmosis: Water Desalination Water desalination plant in Tampa ... 26 Osmosis : Calculating a Molar Mass Dissolve 35.0 g of hemoglobin in enough water to make 1.00 L of solution. measured to be 10.0 mm Hg at 25 C. Calc. molar mass of hemoglobin. hemoglobin. ... 27 ...
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This note was uploaded on 04/15/2008 for the course CHEM 112 taught by Professor Hardy during the Spring '08 term at UMass (Amherst).

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