Review Reaction mechanism Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l)

Slides:

Advertisements

Similar presentations

Reaction Rates What affects the rate of reaction?.

Advertisements

Kinetics Mechanism, Catalysts, and activation Energy.

The next step in kinetics. * Molecules must collide to react. * Concentration affects rates because collisions are more likely. * Must collide hard enough.

Chapter 14 Chemical Kinetics.

 Reactants must collide with proper orientation and sufficient energy.

Collision Theory. Reactions are fastest with… 1.Large Ea, Large T 2.Low Ea, Large T 3.Large Ea, Low T 4.Low Ea, Low T.

Collision Theory. Reaction Coordinate Diagrams Multistep Reactions.

Temperature dependence of reaction rates

Explain that reactions can occur by more than one step and that the slowest step determines the rate of the reaction (rate- determining step)

Ch 15 Rates of Chemical Reactions Chemical Kinetics is a study of the rates of chemical reactions. Part 1 macroscopic level what does reaction rate mean?

Reaction Rates Collision Theory  In order for reactions to occur, particles must collide  If collisions are too gentle, no reaction occurs  If collisions.

Reaction Rate The rate of appearance of a product The rate of appearance of a product or disappearance of a reactant or disappearance of a reactant units:

Chemical Kinetics CHAPTER 14 Part B

Equilibrium Rate Constant Integrated Rate Law Activation Energy Reaction Mechanisms Rate Laws.

Kinetics The Study of Rates of Reaction. Rate of a Reaction The speed at which the reactants disappear and the products are formed determines the rate.

1 Reaction Mechanism The series of steps by which a chemical reaction occurs. A chemical equation does not tell us how reactants become products - it is.

Activation energy. Review of Exothermic Reactants Ep is higher than Products Ep. Now, we must consider the activation energy (the energy needed so that.

13-1 CHEM 102, Spring 2012, LA TECH CTH 328 9:30-10:45 am Instructor: Dr. Upali Siriwardane Office: CTH 311 Phone Office.

Chapter 14 Chemical Kinetics (part 2). The Collision Model Goal: develop a model that explains why rates of reactions increase as concentration and temperature.

Chapter 14 Chemical Kinetics (part 2). The Collision Model Goal: develop a model that explains why rates of reactions increase as concentration and temperature.

Collision Theory. Use the Collision Theory to explain the rate of chemical reactions. Include: Activation energy Draw potential energy diagrams for various.

The Arrhenius Equation AP Chemistry Unit 8 Kinetics.

Activation Energy E a : is the minimum energy that reactants must have to form products. the height of the potential barrier (sometimes called the energy.

Kinetics Concept of rate of reaction

A Nanoscale View: Elementary Reactions A Nanoscale View: Elementary Reactions Most reactions occur through a series of simple steps or elementary reactions.

Collision Theory. Use the Collision Theory to explain the rate of chemical reactions. Include: Activation energy Draw potential energy diagrams for various.

Review Reaction mechanism Br 2 (l) step 1 Br 2 2 Br. h step 2Br. + step 3 C 5 H overall Br 2 C 5 H 12  HBr + C 5 H 11. Br.  C 5 H 11 Br + C 5 H.

13-1 CHEM 102, Spring 2015, LA TECH Instructor: Dr. Upali Siriwardane Office: CTH 311 Phone Office Hours: M,W 8:00-9:30.

© 2009, Prentice-Hall, Inc. Temperature and Rate Generally, as temperature increases, so does the reaction rate. This is because k is temperature dependent.

Chemical Kinetics. Thermodynamics – does a reaction take place? Kinetics – how fast does a reaction proceed? Reaction rate is the change in the concentration.

The Collision Model The reaction rate depends on: collision frequency

Chemical Kinetics Chapter 13.

Chemical Kinetics Unit 10 – Chapter 12.

Reaction Rates The term reaction rate refers to how fast a

Arrhenius equation LO- Carry out calculations involving the Arrhenius equation. So far we have looked quantitatively at how to show the effect of a concentration.

Chemical Kinetics Kinetics – how fast does a reaction proceed?

Ch 13 Reaction Mechanisms

Rates October 2016.

Collision Theory.

Chapter 14 Chemical Kinetics

Dr. Fred Omega Garces Chemistry 201 Miramar College

The Arrhenius equation

CHEMICAL KINETICS Chpt 12

Unit 11- Chemical Kinetics

Temperature and Rate The rates of most chemical reactions increase with temperature. How is this temperature dependence reflected in the rate expression?

Kinetics and Rate Law.

Second-Order Processes

Review Reaction mechanism Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l)

Kinetics Reaction Mechanisms By Adriana Hartmann.

Collision Theory.

Chapter 16.2: Activation Energy

The Arrhenius equation- AP

KINETICS CONTINUED.

A STUDY OF REACTION RATES

Review Reaction mechanism Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l)

Unit 1: Reaction Kinetics

Temperature and Rate The Collision Model

CHEM 3310 Chemical Kinetics Collision Theory & Transition State Theory.

Chemical Kinetics Chapter 13.

Activation energy.

Chemical Kinetics Chapter 13.

Collision Model Goal: develop a model that explains why rates of reactions increase as concentration and temperature increases. The collision model: in.

Bell Work: Kinetics Intro

Chemical Kinetics Chapter 14.

Second-Order Processes

Chapters 16 & 17 Thermochemistry.

H2S (g) + Zn2+ (aq) ⇆ ZnS (s) + 2H+ (aq)

Presentation transcript:

Review Reaction mechanism Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l) step 1 Br2  step 2 Br. + C5H12  HBr + C5H11. C5H11. + Br.  C5H11Br step 3 overall Br2 + C5H12  C5H11Br + HBr

Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l) 2 Br.  step 1 Br2 HBr + C5H11.  step 3 C5H11. + Br. C5H11Br assume step 2 is rate determining (slow) rate = k2 [Br.] [C5H12] Br.= intermediate Keq = [Br.]2 [Br2] rate = k2 k’[Br2]1/2 [C5H12] rate = k’[Br2]1/2 [C5H12] [Br.] = Keq1/2 [Br2]1/2 11/2 order reaction

bimolecular elementary steps increase [react]  increase rate of reaction increase T  increase rate of reaction increase number of collisions increase force of collisions

minimum energy required for reaction: T2 > T1 # molecules Kinetic Energy minimum energy required for reaction: activation energy = Ea

Arrhenius Equation k = z p e-Ea/RT T dependence of a rate constant, k a) increases b) decreases with T k a) decreases b) increases with Ea Ea = activation energy (kJ/mol) R = gas constant (8.314 x 10-3kJ/K mol) T = temperature (K) z = collision frequency p = steric factor (<1)

k = A e-Ea/RT p = steric factor z = collision frequency combine to give A k = A e-Ea/RT

Arrhenius Equation k = A e-Ea/RT ln k = - (Ea/R) (1/T) + ln A ln A y = m x + b plot ln k v.s. 1/T slope = -Ea/R intercept = ln A ln (k2/ k1) = (Ea /R) (1/T1 - 1/T2)

A-B + C A...B...C A + B-C activated complex P.E. is at a maximum transition state A + B-C

Hrxn A-B + C A...B...C A + B-C Eaf Eab activated complex reactants P.E. Hrxn products Reaction coordinate A-B + C A...B...C A + B-C

Hrxn exothermic Eab Eaf > endothermic Eaf Eab activated complex reactants P.E. Hrxn products Reaction coordinate exothermic Eab Eaf > endothermic

exothermic Eab Eaf > large Ea = slow rate endothermic Eab Eaf < activated complex products reactants Eaf Eab P.E. Reaction coordinate exothermic Eab Eaf > large Ea = slow rate endothermic Eab Eaf <

faster forward reaction ( kf ) lowers Ear  - catalyst + catalyst lowers Eaf  faster forward reaction ( kf ) lowers Ear  faster reverse reaction ( kr ) Keq unchanged and H kf = Keq kr

Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l) Hrxn < 0 Ea Reaction coordinate P.E. Br2 + C5H12 Hrxn C5H11Br + HBr

Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l) step 1 Br2 2 Br. hn Br2(l) + C5H12(l)  C5H11Br(l) + HBr(l) step 1 Br2 2 Br. h step 2 Br. + C5H12  HBr + C5H11. step 3 C5H11. + Br.  C5H11Br Ea Ea Ea HBr + C5H11. + Br. 2Br. + C5H12 C5H12 + Br2 P.E. C5H11Br + HBr