CHEM 1442 1st Edition Lecture 8Outline of Last Lecture I. KineticsOutline of Current Lecture II. Raoult’s LawIII. Reaction MechanismIV. CatalystsCurrent LectureRaoult’s LawThe vapor pressure of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent at that temperature multiplied by its mole fraction.p = xsolvent x PosolventPo is the vapor pressure of the pure solvent at a particular temperature.Xsolvent is the mole fraction of the solventXsolvent = moles of solvent / total number of molesReaction MechanismMost chemical reactions occur through a “reaction mechanism.”Reaction mechanism – “step-by-step descriptions of what occurs in chemical reactions”*Remember the three things needed for a reaction to occur: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.- A and B need to meet- A and B must have enough energy- A and B have to be in the correct orientationHowever, termolecular reactions where three molecules meet are very rare; this is due to the orientation.Instead, there is a reaction mechanism.Example:Reaction Mechanism:Step 1: NO2 (g) + F2 (g)  NO2F (g) + F (g) (“bimolecular” reaction)Step 2: NO2 (g) + F (g)  NO2F (g) (followed with another “bimolecular” reaction)Overall: 2NO2 (g) + F2 (g)  2NO2F (g)The steps in the reaction mechanism are known as “elementary steps/ reactions.”For the elementary reaction,Reaction Order = Stoichiometric CoefficientRate of the overall reaction = Rate of the “Rate-determining” step (slowest reaction)How does a catalyst work?Catalyst: a substance that increases the rate without being consumedExample:Ozone DestructionReaction Mechanism:Step 1: O3 (g) + Cl (g)  O2 (g) + ClO (g) [slow]Step 2: O (g) + ClO (g)  O2 (g) + Cl (g) [fast]Overall: O3 (g) + O (g)  2O2 (g) *Difference between intermediates and catalysts is that intermediate first appears a product and then as a reactant, whereas a catalyst appears in the reactants and ends in the