logging in or signing up lecture10 Melinda Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 2835 Category: Entertainment License: All Rights Reserved Like it (1) Dislike it (0) Added: October 15, 2007 This Presentation is Public Favorites: 2 Presentation Description No description available. Comments Posting comment... By: babenawan (7 month(s) ago) may i download pls?, nice ppt Saving..... Post Reply Close Saving..... Edit Comment Close By: karuna56 (9 month(s) ago) plz allow me to download this presentation please!!! Saving..... Post Reply Close Saving..... Edit Comment Close By: Wakasa (11 month(s) ago) May I download please! Saving..... Post Reply Close Saving..... Edit Comment Close By: rnicolosi (15 month(s) ago) May I down load this powerpoint. Thank you. Saving..... Post Reply Close Saving..... Edit Comment Close By: sam18 (18 month(s) ago) May i download it; please Saving..... Post Reply Close Saving..... Edit Comment Close loading.... See all Premium member Presentation Transcript Chemical Kinetics: Chemical Kinetics Chemistry 4th Edition McMurry/FayReaction Mechanisms : Reaction Mechanisms A reaction mechanism is a sequence of molecular events, or reaction steps, that defines the pathway from reactants to products. OH-(aq) + CH3Cl(aq) CH3OH(aq) + Cl-(aq)Reaction Mechanisms : Reaction Mechanisms NO2(g) + CO(g) NO(g) + CO2(g) Reaction NO2(g) + NO2(g) NO(g) + NO3(g) Elementary NO3(g) + CO(g) NO2(g) + CO2(g) Elementary NO2(g) + CO(g) NO(g) + CO2(g) OverallReaction Mechanisms : Reaction Mechanisms Molecularity: is the number of reactants. Unimolecular: Single reactant molecule.Reaction Mechanisms : Reaction Mechanisms Bimolecular: Two reactant molecules. Termolecular: Three reactant molecules.Reaction Mechanisms : Reaction Mechanisms What is the overall reaction?Reaction Mechanisms : Reaction Mechanisms What are the reaction intermediates?Reaction Mechanisms : Reaction Mechanisms What is the molecularity of each of the elementary reactions?Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Rate law for an overall reaction must be determined experimentally. Rate law for an elementary step follows from its molecularity.Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms The rate law of each elementary step follows its molecularity. The overall reaction is a sequence of elementary steps called the reaction mechanism. Therefore, the experimentally observed rate law for an overall reaction must depend on the reaction mechanism.Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms The following substitution reaction has a first-order rate law: Co(CN)5(H2O)2–(aq) + I–(aq) Co(CN)5I3–(aq) + H2O(l) Rate = k[Co(CN)5(H2O)2–] Suggest a mechanism in accord with the rate law. Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Co(CN)5(H2O)2–(aq) + I–(aq) Co(CN)5I3–(aq) + H2O(l) Co(CN)52–(aq) + I–(aq) Co(CN)5I3–(aq) (fast) Co(CN)5(H2O)2–(aq) Co(CN)52–(aq) + H2O(l) (slow) Two-Step Mechanism k1 k2 k1Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Similar to limiting reactant problems (page 89) Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Quote the Authors: Quote the Authors “It’s easy to disprove a mechanism, but it’s never possible to finally “prove” a mechanism ...” Nobel Prize in 1999: Nobel Prize in 1999 Ahmed ZewailNobel Prize in 1999: Nobel Prize in 1999 Ahmed ZewailNobel Prize in 1999: Nobel Prize in 1999 Ahmed ZewailReaction Rates and Temperature : Reaction Rates and Temperature Kuwait ‘91 Refrigerators ‘20sReaction Rates and Temperature : Reaction Rates and Temperature Collision Theory: A bimolecular reaction occurs when two correctly oriented molecules collide with sufficient energy. Activation Energy (Ea): The potential energy barrier that must be surmounted before reactants can be converted to products.The Arrhenius Equation : The Arrhenius Equation The Arrhenius Equation : The Arrhenius Equation How often do collisions occur? Does every single collision between reactants result in products?Physical Chemistry: Physical ChemistryPhysical Chemistry: Physical Chemistry The Collision Frequency of CO2 at STP roughly 7 billion collisions per secondThe Arrhenius Equation : The Arrhenius Equation Fraction of reactive collisionsThe Arrhenius Equation : The Arrhenius Equation roughly 7 collisions in 100 trillion will be reactiveThe Arrhenius Equation : The Arrhenius Equation Orientation - Collision factor pThe Arrhenius Equation : The Arrhenius Equation The Arrhenius Equation : The Arrhenius Equation The Arrhenius Equation : The Arrhenius Equation 2 HI (g) H2 (g) + I2 (g)The Arrhenius Equation : The Arrhenius Equation 2 HI (g) H2 (g) + I2 (g)The Arrhenius Equation : The Arrhenius Equation 2 HI (g) H2 (g) + I2 (g)The Arrhenius Equation : The Arrhenius Equation Interesting Problem : Interesting Problem A common rule of thumb in organic chemistry is that increasing the temperature of a reaction at room temperature by 10°C doubles the rate. Calculate Ea for a reaction that follows this rule of thumb. Assume room temperature is 25°C. Catalysis : Catalysis A catalyst is a substance that increases the rate of a reaction without being consumed in the reaction.Catalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) ThermodynamicsCatalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) Thermodynamics Appendix B in textbookCatalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) Reaction Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall KineticsCatalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) Reaction Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) Slow Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) Fast 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall KineticsCatalysis : Catalysis Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) (Slow) Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) (Fast) 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall H2O2 oxidizes I- to IO- Oxidation - lose electrons Reduction - gain electrons +1 -1 -1 -2 +1Catalysis : Catalysis Observed Rate Law 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) (Slow) Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) (Fast)Catalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g)Catalysis : Catalysis Homogeneous Catalyst: Exists in the same phase as the reactants. Heterogeneous Catalyst: Exists in different phase to the reactants.Surface Catalysis : Surface Catalysis Catalytic HydrogenationCatalysis : Catalysis Radiocarbon Dating : Radiocarbon Dating The age of any remains from a once-living organism can be determined by radiocarbon dating, a procedure that works by determining the concentration of radioactive 14C in the remains. All living organisms contain an equilibrium concentration of radioactive 14C that gives rise to an average of 15.3 nuclear decay events per minute per gram of carbon. At death, however, no additional 14C is taken in, so the concentration slowly drops as radioactive decay occurs.Radiocarbon Dating : Radiocarbon Dating What is the age of a bone fragment from an archaeological dig if the bone shows an average of 2.3 radioactive events per minute per gram of carbon? Radioactive decay is kinetically a first-order process, and t1/2 for 14C is 5730 years.Radiocarbon Dating : Radiocarbon Dating You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
lecture10 Melinda Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 2835 Category: Entertainment License: All Rights Reserved Like it (1) Dislike it (0) Added: October 15, 2007 This Presentation is Public Favorites: 2 Presentation Description No description available. Comments Posting comment... By: babenawan (7 month(s) ago) may i download pls?, nice ppt Saving..... Post Reply Close Saving..... Edit Comment Close By: karuna56 (9 month(s) ago) plz allow me to download this presentation please!!! Saving..... Post Reply Close Saving..... Edit Comment Close By: Wakasa (11 month(s) ago) May I download please! Saving..... Post Reply Close Saving..... Edit Comment Close By: rnicolosi (15 month(s) ago) May I down load this powerpoint. Thank you. Saving..... Post Reply Close Saving..... Edit Comment Close By: sam18 (18 month(s) ago) May i download it; please Saving..... Post Reply Close Saving..... Edit Comment Close loading.... See all Premium member Presentation Transcript Chemical Kinetics: Chemical Kinetics Chemistry 4th Edition McMurry/FayReaction Mechanisms : Reaction Mechanisms A reaction mechanism is a sequence of molecular events, or reaction steps, that defines the pathway from reactants to products. OH-(aq) + CH3Cl(aq) CH3OH(aq) + Cl-(aq)Reaction Mechanisms : Reaction Mechanisms NO2(g) + CO(g) NO(g) + CO2(g) Reaction NO2(g) + NO2(g) NO(g) + NO3(g) Elementary NO3(g) + CO(g) NO2(g) + CO2(g) Elementary NO2(g) + CO(g) NO(g) + CO2(g) OverallReaction Mechanisms : Reaction Mechanisms Molecularity: is the number of reactants. Unimolecular: Single reactant molecule.Reaction Mechanisms : Reaction Mechanisms Bimolecular: Two reactant molecules. Termolecular: Three reactant molecules.Reaction Mechanisms : Reaction Mechanisms What is the overall reaction?Reaction Mechanisms : Reaction Mechanisms What are the reaction intermediates?Reaction Mechanisms : Reaction Mechanisms What is the molecularity of each of the elementary reactions?Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Rate law for an overall reaction must be determined experimentally. Rate law for an elementary step follows from its molecularity.Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms The rate law of each elementary step follows its molecularity. The overall reaction is a sequence of elementary steps called the reaction mechanism. Therefore, the experimentally observed rate law for an overall reaction must depend on the reaction mechanism.Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms The following substitution reaction has a first-order rate law: Co(CN)5(H2O)2–(aq) + I–(aq) Co(CN)5I3–(aq) + H2O(l) Rate = k[Co(CN)5(H2O)2–] Suggest a mechanism in accord with the rate law. Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Co(CN)5(H2O)2–(aq) + I–(aq) Co(CN)5I3–(aq) + H2O(l) Co(CN)52–(aq) + I–(aq) Co(CN)5I3–(aq) (fast) Co(CN)5(H2O)2–(aq) Co(CN)52–(aq) + H2O(l) (slow) Two-Step Mechanism k1 k2 k1Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Similar to limiting reactant problems (page 89) Rate Laws and Reaction Mechanisms : Rate Laws and Reaction Mechanisms Quote the Authors: Quote the Authors “It’s easy to disprove a mechanism, but it’s never possible to finally “prove” a mechanism ...” Nobel Prize in 1999: Nobel Prize in 1999 Ahmed ZewailNobel Prize in 1999: Nobel Prize in 1999 Ahmed ZewailNobel Prize in 1999: Nobel Prize in 1999 Ahmed ZewailReaction Rates and Temperature : Reaction Rates and Temperature Kuwait ‘91 Refrigerators ‘20sReaction Rates and Temperature : Reaction Rates and Temperature Collision Theory: A bimolecular reaction occurs when two correctly oriented molecules collide with sufficient energy. Activation Energy (Ea): The potential energy barrier that must be surmounted before reactants can be converted to products.The Arrhenius Equation : The Arrhenius Equation The Arrhenius Equation : The Arrhenius Equation How often do collisions occur? Does every single collision between reactants result in products?Physical Chemistry: Physical ChemistryPhysical Chemistry: Physical Chemistry The Collision Frequency of CO2 at STP roughly 7 billion collisions per secondThe Arrhenius Equation : The Arrhenius Equation Fraction of reactive collisionsThe Arrhenius Equation : The Arrhenius Equation roughly 7 collisions in 100 trillion will be reactiveThe Arrhenius Equation : The Arrhenius Equation Orientation - Collision factor pThe Arrhenius Equation : The Arrhenius Equation The Arrhenius Equation : The Arrhenius Equation The Arrhenius Equation : The Arrhenius Equation 2 HI (g) H2 (g) + I2 (g)The Arrhenius Equation : The Arrhenius Equation 2 HI (g) H2 (g) + I2 (g)The Arrhenius Equation : The Arrhenius Equation 2 HI (g) H2 (g) + I2 (g)The Arrhenius Equation : The Arrhenius Equation Interesting Problem : Interesting Problem A common rule of thumb in organic chemistry is that increasing the temperature of a reaction at room temperature by 10°C doubles the rate. Calculate Ea for a reaction that follows this rule of thumb. Assume room temperature is 25°C. Catalysis : Catalysis A catalyst is a substance that increases the rate of a reaction without being consumed in the reaction.Catalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) ThermodynamicsCatalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) Thermodynamics Appendix B in textbookCatalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) Reaction Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall KineticsCatalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g) Reaction Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) Slow Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) Fast 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall KineticsCatalysis : Catalysis Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) (Slow) Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) (Fast) 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall H2O2 oxidizes I- to IO- Oxidation - lose electrons Reduction - gain electrons +1 -1 -1 -2 +1Catalysis : Catalysis Observed Rate Law 2 H2O2 (aq) 2 H2O (l) + O2 (g) Overall Step 1. H2O2 (aq) + I- (aq) H2O (l) + IO- (aq) (Slow) Step 2. H2O2 (aq) + IO- (aq) H2O (l) + O2 (g) + I- (aq) (Fast)Catalysis : Catalysis 2 H2O2 (aq) 2 H2O (l) + O2 (g)Catalysis : Catalysis Homogeneous Catalyst: Exists in the same phase as the reactants. Heterogeneous Catalyst: Exists in different phase to the reactants.Surface Catalysis : Surface Catalysis Catalytic HydrogenationCatalysis : Catalysis Radiocarbon Dating : Radiocarbon Dating The age of any remains from a once-living organism can be determined by radiocarbon dating, a procedure that works by determining the concentration of radioactive 14C in the remains. All living organisms contain an equilibrium concentration of radioactive 14C that gives rise to an average of 15.3 nuclear decay events per minute per gram of carbon. At death, however, no additional 14C is taken in, so the concentration slowly drops as radioactive decay occurs.Radiocarbon Dating : Radiocarbon Dating What is the age of a bone fragment from an archaeological dig if the bone shows an average of 2.3 radioactive events per minute per gram of carbon? Radioactive decay is kinetically a first-order process, and t1/2 for 14C is 5730 years.Radiocarbon Dating : Radiocarbon Dating