CHEM 251 1st Edition Lecture 16 Outline of Last Lecture I. Clicker QuestionII. Group ProblemsOutline of Current Lecture III. Clicker QuestionsIV. Chemical ReactionsV. CatalysisVI. Calculating Reaction ThermodynamicsVII. Thermochemical CycleCurrent LectureVIII. Clicker Questionsa. What thermodynamic quantity describes: Na(s) => Na(g)i. Enthalpy of Atomization (energy required to produce 1 mol gaseous atoms from elements)ii. Enthalpy of Vaporization (liquid to gas)iii. Enthalpy of Fusion (solid to liquid)iv. Lattice Enthalpy (ionic lattice formation)IX. Chemical Reactionsa. ΔH = change in enthalpy; how much heat is produced/consumed?i. Positive = endothermic, consumes heatii. Negative = exothermic, produces heatb. ΔS = change in entropy; are the products more or less ordered?c. ΔG = change in Gibbs free energy; ΔG = ΔH - TΔSi. Positive = endergonic, requires energy (non-spontaneous)ii. Negative = exergonic, releases energy (spontaneous)d. Reaction coordinate diagram: mapping the energy of each species through the 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.i.ii. ΔG=negative, reaction is spontaneous/exergonic iii. Example: Methane to graphite and hydrogen1.2. ΔH = positive, reaction is endothermic3. The reverse reaction must release lots of heat, but why doesn’t this spontaneously happen?a. Kinetic barrieri. How much energy must be put in to get the reaction to goii. Determine how quickly reaction happens; reaction rateiii. Affected by temperature, solvent, etc.iv.1. Lowest energy pathway in 3D contour is path we draw when considering kinetics X. Catalysisa. Speeds up reaction w/out being consumedb. Thermodynamics unchangedc. Can either lower kinetic barrier or add a new pathwayd.XI. Calculating Reaction Thermodynamicsa. Option 1-measure energy consumed or releasedb. Option 2-combine standard/known reactions c. Enthalpy of Formation: how much energy released/consumed to form molecule from its elementsi. For all elemental forms = 0ii. Σ(Enthalpy or products) – Σ(enthalpy of reactants) = ΔHºrxnd. Bond Enthalpiesi. Enthalpy required to break a bond (appendix 3)ii. Higher bond order => higher bond strengthiii. Useful when bonds broken/formediv. Always positive (leaves unstable radicals)e. Lattice enthalpyi. Enthalpy of formation of an ionic solid from gas-phase ionsii. Affected by lattice structure, distances between attractive/repulsive interactions, ion chargesiii. Appendix 6iv. Born-Lande Equationv.vi. Useful for reaction involving solid saltvii. Always negative f. Enthalpy of atomizationi. Enthalpy to produce 1 mol gaseous atoms from elementii. Equivalent to enthalpy of formation of atomic gasiii. Useful for moving metal lattices to gas phase atomsiv. Useful for moving elemental to atomic formsg. Enthalpy of vaporizationi. From liquid to gash. Enthalpy of hydrationi. Solid/liquid/gas to aqueousi. Entropyi. Amount of disorder in moleculeii. ΔSºrxn = ΣSº(products) – ΣSº(reactants)j. Gibbs Free Energyi. Specific to temperatureii. ΔGº = ΔH – TΔSºiii. ΔGºrxn = ΣΔGº(products) – ΣΔGº(reactants)XII. Thermochemical