Warm Up Calculate the expected vapor pressure at 25oC for a solution prepared by dissolving 158.0 g of common table sugar (sucrose = 342.3 g/mol) in 643.5 cm3 of water. At 25oC, the density of water is 0.9971 g/cm3 and the vapor pressure is 23.76 torr. Psoln = CH2OP0H2O Mole fraction H2O= 35.63 mol sucrose 35.63 mol + .4616mol = 0.9873 Psoln = (0.9873)(23.76 torr) = 23.46 torr Vapor pressure has lowered from 23.76 to 23.46 torr

Freezing Point Depression & Boiling Point Elevation https://video.search.yahoo.com/video/play;_ylt=A2KLqIMJNfdUegEAHO_7w8QF;_ylu=X3oDMTByZ2N0cmxpBHNlYwNzcgRzbGsDdmlkBHZ0aWQDBGdwb3MDMg--?p=boiling+point+elevation+freezing+point+depression&vid=6384124179d91307101986432969ca2e&l=10%3A01&turl=http%3A%2F%2Fts3.mm.bing.net%2Fth%3Fid%3DVN.608005256063748274%26pid%3D15.1&rurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIYTwOd30vdA&tit=Boiling+Point+Elevation+and+Freezing+Point+Depression+from+Thinkwell+Chemistry&c=1&sigr=11bb5hgiv&sigt=12eqlt2a9&sigi=11ru4f10k&age=1362638816&fr2=p%3As%2Cv%3Av&hsimp=yhs-001&hspart=mozilla&tt=b https://video.search.yahoo.com/video/play;_ylt=A2KLqIVrNPdUgjAAAL_7w8QF;_ylu=X3oDMTBzZWQ1aGR0BHNlYwNzcgRzbGsDdmlkBHZ0aWQDBGdwb3MDMTI-?p=boiling+point+elevation+freezing+point+depression&vid=bd78466a0de2449c6ef32c35c6559682&l=5%3A43&turl=http%3A%2F%2Fts2.mm.bing.net%2Fth%3Fid%3DVN.607991224405658737%26pid%3D15.1&rurl=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D51VM41qLuIc&tit=Colligative+Properties+Ex-+Boiling+Point+Elevation-Freezing+point+Depression&c=11&sigr=11a341r9m&sigt=12c0stb4u&sigi=11rms6epa&age=1424971960&fr2=p%3As%2Cv%3Av&hsimp=yhs-001&hspart=mozilla&tt=b

Simulation http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/propOfSoln/colligative.html

HW Define Colligative Properties p. 522 #46 & 60.

Non-Ideal Raoult’s Law What if both liquids are volatile and contribute to the vapor pressure? Occasionally, they will react and produce less pressure than is expected. Ptotal = PA + PB + PC + …

Example A solution is prepared by mixing 5.81 g acetone (C3H6O, molar mass = 58.1 g/mol) and 11.9 g chloroform (HCCl3, molar mass = 119.4 g/mol). At 35oC, this solution has a total vapor pressure of 260. torr. Is this an ideal solution? The vapor pressure of pure acetone and pure chloroform at 35oC are 345 and 293 torr respectively. Hint: Calculate expected pressure, compare it to actual. 0.100 mol acetone, 0.100 mol chloroform Now, calc mole fractions. Ptot = (Xacetone)(Poacetone)+(Xchloroform)(Pochloroform) Ptot = (.500)(345) + (.500)(293) = 319 torr

Example (cont.) Ptot = (.500)(345) + (.500)(293) = 319 torr This is lower than the 260 torr shown in the experiment. This means there are interactions between the acetone and chloroform in the solution and they are less likely to become a vapor.

11.8 Suspensions and Colloids Suspensions and colloids are NOT solutions. Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred. Colloids: The particles intermediate in size between those of a suspension and those of a solution.

Types of Colloids Examples Dispersing Medium Dispersed Substance Colloid Type Fog, aerosol sprays Gas Liquid Aerosol Smoke, airborn germs Solid Whipped cream, soap suds Foam Milk, mayonnaise Emulsion Paint, clays, gelatin Sol Marshmallow, Styrofoam Solid Foam Butter, cheese Solid Emulsion Ruby glass Solid sol

The Tyndall Effect Colloids scatter light, making a beam visible. Solutions do not scatter light. Which glass contains a colloid? colloid solution

HW Colligative Properties 11.7 wkst