CHEM 1120 1st Edition Exam 1 Study Guide Lectures 1 11 Lecture 1 Vocabulary or Concept Definition or Explanation Solvent Majority of a solution what substance is being dissolved in Solute Least part of a solution what is being dissolved Solvating Solvent pulling the solute particles apart how a solution forms Intermolecular Forces Forces between different molecules Solutions will only form Solution of A and B will only form if A B attractions are comparable if in strength to A A and B B attractions if not they won t mix i e water and oil Ion Dipole force Strongest intermolecular force ion and dipole interact Hydrogen bonding Hydrogen bonds to N O F Dipole dipole 2 dipoles interacting Ion induced dipole Bring a charge next to something that doesn t have a dipole causes it to become a dipole Take charge away dipole goes away Less common Dipole induced dipole Less common similar to ion induced Dispersion forces At an instantaneous point molecule has a charge Weakest intermolecular force 3 steps to substances dissolving ex NaCl in water 1 NaCl crystals separate into ions Endothermic process 2 Water molecules create holes to accommodate Na and Clions endothermic 3 Na and Cl ions enter the holes exothermic H of Solution H of solute H of solvent H of mixing Unsaturated Add more of a solute to a solvent and it dissolves less solute than can dissolve in the solvent Supersaturated Add more and it crystalizes solvent hold more solute than is normally possible very unstable Saturated At equilibrium most solute that the solvent can possibly hold Equations H of Solution H of solute H of solvent H of mixing Lecture 2 Vocabulary or Concept Definition or Explanation Solubility Maximum amount of solute dissolved in a given amount of solvent at temperature T Like dissolves like Similar things dissolve good rule of thumb for solubility Effect of Temperature on Solubility Solids Higher temperature greater solubility Henry s Law Gas solubility is directly proportional to the gas pressure over the solution Solubility of gas mol L k mol Latm x Pressure of the gas atm Molarity M Moles of solute Liters of solution Molality m Moles of solute kg of solvent independent of temperature Mass percent w w Mass of component total mass of solution x 100 Gases Higher temperature lower solubility Volume percent v v Volume of component volume of solution x 100 need densities to solve equations using this Mole fraction X Mole fraction of A moles of A total moles of all components Parts per million ppm and parts per billion ppb Ppm of component Mass of component total mass of solution x 10 6 Colligative properties Solution properties that depend ONLY upon the number of the solute particles not their nature or identity i e vapor pressure lowering osmosis freezing point depression boiling point elevation Ppb of component mass of component total mass of solution x 10 9 Raoult s Law vapor pressure lowering Pa XaPoa where Pa solvent v p Xa solvent mole fraction and Poa pure solvent v p Equations Solubility of gas mol L k mol Latm x Pressure of the gas atm Molarity M moles of solute Liters of solution Molality m moles of solute kg of solvent Mass percent w w Mass of component total mass of solution x 100 Volume percent v v Volume of component volume of solution x 100 Mole fraction X of A moles of A total moles of all components Ppm of component Mass of component total mass of solution x 10 6 Ppb of component mass of component total mass of solution x 10 9 Pa XaPoa Lecture 3 Vocabulary or Concept Definition or Explanation More on Raoult s Law Change in Pa Xb x Poa where A solvent and B solute strong solute solvent interactions negative deviations from raoult s law Change in boiling point elevation Tb Kb x m Change in freezing point depression Tf Kf x m depend on solvent not solute Osmosis Diffusion of solvent through semi permeable membrane into a solution of higher concentration Osmotic pressure MRT Colligative Properties of Electrolyte solutions Electrolytes do not completely dissociate use Vant Hoff Factor Van t Hoff Factor i Change in Tf measured Change in Tf expected for nonelectrolyte Suspension Heterogeneous mixture with dispersed particles large enough to be seen Colloid A mixture with dispersed particles larger than a solution s but smaller than a suspensions Ex Fog clouds butter marshmallows paint whipped cream milk Tyndall Effect Colloidal suspensions can scatter rays of light Hydrophilic colloids Water loving easily dispersed in water Hydrophobic colloids Must be stabilized by ions absorbed on the particle s surface or by hydrophilic groups in the particle s surface Equations Change in Pa Xb x Poa Tb Kb x m Tf Kf x m MRT Van t Hoff Factor i Change in Tf measured Change in Tf expected for nonelectrolyte Lecture 4 Vocabulary or Concept Definition or Explanation Reaction Rate 1 a A t 1 b B t 1 c C t 1 d D t Where reaction is aA bB cC dD measured in units of concentration per time i e M s Rate law Rate k x A m x B n Where reaction is aA bB cC dD m and n are order of the reaction Factors the affect speed of a reaction Reactant physical state reactant concentration temperature catalysts Average Rate vs Instantaneous Rate Rate of reaction averaged over a period of time vs rate at an arbitrarily short time at a particular point in time tangent to curve Units of rate constants Units of rate units of rate constant Units of concentration order Equations 1 a A t 1 b B t 1 c C t 1 d D t Rate k x A m x B n Units of rate units of rate constant Units of concentration order Lecture 5 Vocabulary or Concept Definition or Explanation Method of initial Rates Determine reaction orders from the effect of changing a reactant s concentration on the initial rate of the reaction How to calculate rate order Rate 2 Rate 1 A n x B m x C p for rate 2 A n x B m x C p for rate 1 solve for m and n Integrated rate laws 0th order A at time t kt A initially 1st order Ln A kt ln A initially 2nd order 1 A kt 1 A initially Confirming 1st order reactions using concentration vs time Graph should exponentially decay graph t vs ln A linear first order reaction slope of line is rate constant Confirming 2nd order reactions using concentration vs time Plot t against 1 A linear 2nd order reaction Equations Rate 2 Rate 1 A n x B m x C p for rate 2 A n x B m x C p for rate 1 0th order A at time t kt A initially 1st order Ln A kt ln A initially 2nd order 1 A kt 1 A initially Lecture 6 Vocabulary or Concept Definition or Explanation Half life t1 2 The time