CHEM 1120 1st Edition Lecture 3 Outline of Last Lecture I Solubility and Saturation II Effects of Pressure and Temperature on Solubility a Temperature i Solid solutions ii Gaseous solutions b Gas Solubility and Pressure III Concentration Units a Molarity M b Molality m c Mass Percent w w d Volume Percent v v e Mole Fraction X f Parts per million ppm and Parts per billion ppb IV Colligative Properties a Vapor pressure lowering b Raoult s Law Outline of Current Lecture I Colligative Properties Continued from Last Lecture a Vapor Pressure lowering continued b Boiling Point Elevation and Freezing Point Depression c Osmosis II Colligative Properties of Electrolyte solutions a Dependent on number of ions III Colloids a What they are b Tyndall Effect These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute c Hydrophilic and Hydrophobic colloids IV Begin Chapter 14 Intro to chapter Current Lecture I Colligative Properties Continued a Vapor Pressure lowering continued i Change in Pa Xb x Poa 1 A solvent 2 B solute ii Change in Pa vapor pressure lowering iii Strong solute solvent interactions NEGATIVE deviations from Raoult s Law and vice versa b Boiling Point Elevation and Freezing Point Depression i Change in boiling point elevation molal BP elevation constant x molality 1 Tb Kb x m ii Change in freezing point depression molal FP depression constant x molality 1 Tf Kf x m iii Tb and Tf depends on solvent NOT solute iv To find freezing point 1 Calculate Change in Tf and subtract that number from normal freezing point c Osmosis i Examples 1 Nutrient transport in plants and animals 2 Limp carrots regain their crispiness in water 3 Cucumbers shrivel to become pickles in brine 4 Meat is preserved in salt bacteria dehydrated 5 Water is purified reverse osmosis ii Osmosis diffusion of solvent through a semi permeable membrane into a solution of higher concentration iii Semipermeable membrane a membrane that allows passage of solvent molecules but not solute molecules iv Osmotic Pressure pi 1 Pi V nRT 2 Similar to ideal gas law 3 Osmotic pressure MRT 4 M molarity v Osmosis in blood cells 1 Osmotic pressure is same on both sides isotonic 2 Solute concentration outside is greater than inside hypertonic cell depletes II III IV V 3 Solute concentration outside is less than inside hypotonic Cell bursts Colligative Properties of Electrolyte Solutions a Salt solutions and the NUMBER of solute particles i NaCl Na Cl 1 mol 2 mol ii Depends on particles iii Number of ions per formula unit is important iv Electrolytes do not COMPLETELY dissociate v Van t Hoff Factor i Change in Tf measured Change in Tf expected for nonelectrolyte 1 More charge more likely to have ionic association 2 Lower concentration closer to theoretical vi VP lowering Pa I x Xb x Poa vii PB elevation Tb I x Kb x m viii FB depression Tf I x Kf x m ix Osmotic pressure pi I x M x R x T Colloids a Suspension a heterogeneous mixture with dispersed particles large enough to be seen b Colloid a mixture with dispersed particles larger than a solution s but smaller than a suspensions i Particle diameter in nm 1 1000 ii Example fog clouds about 600 nm butter marshmallows paint whipped cream milk iii Colloids do not have to be liquids c Tyndall Effect i Colloidal suspensions can scatter rays of light known as Tyndall Effect d Hydrophilic and hydrophobic colloids i Hydrophilic water loving 1 Easily dispersed in water 2 Core may be hydrophobic but as long as surface is hydrophilic it is dispersed in water ii Hydrophobic water fearing 1 Must be stabilized by ions absorbed on the particle s surface or by hydrophilic groups in the particles surface CHAPTER 14 START Chemical Kinetics Chapter Intro a Thermodynamics only tells you if it should happen but doesn t tell you how long b How can we modify reactions to go faster