CH 221 1st Edition Lecture 16 Outline of Last Lecture I. StereoisomersII. CycloalkenesIII. Vinylic and Allylic CarbonsIV. E, Z system of NomenclatureOutline of Current Lecture V. EletrophilesVI. NucleophilesVII. Two Step ReactionsVIII. Thermodynamics and KineticsIX. EquilibriumX. Gibb’s Free Energy XI. Rates of ReactionCurrent LectureV. An electrophile has a positive charge, a partial positive charge, or an incomplete octet- Ex. +¿H¿ or +¿ CH2CH3¿ have positive charge- Ex. BH3 has an incomplete octetVI. Nucleophiles have a negative charge or lone pair- Nucleophiles react with electrophiles- Ex. −¿OH¿, −¿Cl¿, CH3NH2, H2O all because they have electrons available to shareVII. Two Step Reactions- Curved arrows used to show mechanics of a reactionThese 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.- Mechanism of a reaction is a step-by-step description of the process by which the reactants are converted into products- σ bond breaks, π bond breaks, σ bond formed- Second step forms σ bond- Curved arrows show where electrons start and where they endVIII. Thermodynamics and Kinetics- Y ↔ Z - Thermodynamics: how much Z is formed- Kinetics: how fast Z is formed- A reaction coordinate diagram shows the energy changes that take place in each step of a reactionIX. Equilibrium Constant- gives concentration of reactants and products at equilibrium- m A + n B ↔ s C + t D- Keq = [ products][reactants]- Keq = [C ]s[ D]t[ A ]m[ B]n- Can be endergonic or exergonic- ∆Gº = -RT ln KeqX. Gibb’s Free Energy (∆Gº) - ∆Gº = ∆Hº - T∆Sº- Free energy of products – free energy of reactants- ∆Hº = heat required to break bonds – heat released from bonds breaking- ∆Sº = freedom of motion of products – freedom of motion of reactants- Free energy of activation ∆Gⱡ- ∆Gⱡ = ∆Hⱡ - T∆Sⱡ- ∆Hⱡ = enthalpy of transition state – enthalpy of reactants- The free energy of activation is the energy barrier of the reactionXI. Rates of Reactions- Increasing concentrations increases rate- Increasing temperature increases rate- Rate can also be increased by a catalyst- Rate of reaction = (number of collisions per unit of time) x (fraction with sufficient energy) x (fraction with proper orientation)- A B (first order reaction) rate = k[A]- K is the rate constant and rate is the rate of the reaction- A + B C + D (second order reaction) rate = k[A][B]- K is the rate constant and rate is the rate of the
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