Catalysts: Speed up reaction rates by offering an alternate reaction pathway with a lower activation energy How they work … Remember “collision theory”

Slides:

Advertisements

Similar presentations

Reaction Rates What affects the rate of reaction?.

Advertisements

Collision Theory For a rx to occur reacting molecules must collide so 1 - The old bonds “loosen up”, or start to break apart 2 - The correct orientation.

First premise: Reactants must collide in order to react and form products. A 2 + B 2 2 AB Collision Theory.

Reaction Rates, Catalysts and Collision Theory. Rates of reaction The rate of a reaction measures how fast it happens. Increased reaction rate means that.

Unit 7 Notes Part 1 Chemical Kinetics The area of chemistry concerned with the speed at which reactions occur is called chemical kinetics. – Reaction.

Chemical Kinetics and Chemical Equilibrium Read in Ch. 22: Reaction Rates pp Equilibrium pp Honors: Ch. 17 and 18.

 Reactants must collide with proper orientation and sufficient energy.

1 What is the collision theory, and how does it relate to reaction rates? Particles must collide and break the existing bonds so they can form new ones.

Section 2.8—Speeding Up A Reaction

Chapter 17.1 How chemical reactions occur. Molecules react by colliding. 2 BrNO  2 NO + Br 2 1. Two BrNO molecules approach each other at high speeds.

The final saga.  There is an activation energy for each elementary step.  Activation energy determines k.  k = Ae - (E a /RT)  k determines rate 

Chemical Kinetics Chapter 15 H 2 O 2 decomposition in an insect H 2 O 2 decomposition catalyzed by MnO 2.

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

Chemical Kinetics Chapter 17 Chemical Kinetics Aka Reaction Rates.

Reaction Rates and Equilibrium

Reaction Rate How Fast Does the Reaction Go Collision Theory Chemists believe that all chemical change (rearrangement of matter) occurs due to the collision.

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.

Reaction Mechanics. Explain the concept of a reaction mechanism. Include: rate determining step, potential energy diagrams Additional KEY Terms Bimolecular.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Chemistry FIFTH EDITION by Steven S. Zumdahl University of Illinois.

Collision Theory & Reaction Mechanisms

Unit 9 – Reaction Rates and Equilibrium The area of chemistry that concerns reaction rates (how fast a reaction occurs)

Chemical Kinetics. Collision Theory of Reactions Collision theory is simple - for a reaction to occur, particles must collide successfully! A successful.

Thermodynamics Tells if a reaction will occur. Kinetics Tells how fast a reaction will occur.

Catalysts. Things that Effect Rate l Catalysts- substances that speed up a reaction without being used up.(enzyme). l Speeds up reaction by giving the.

Reaction mechanisms and catalysts

Chemical Kinetics The speed with which chemical reactions occur depends on external conditions The area of chemistry concerned with the speed at which.

Reaction Rate How Fast Does the Reaction Go 5-1. Collision Theory Chemists believe that all chemical change (rearrangement of matter) occurs due to the.

Reaction Process. A reaction mechanism is a step by step sequence of reactions that show an overall chemical change The same reaction can occur by different.

Unit 11 Review Created by Mrs. Martin. 1. List the 6 factors that affect the rate of a reaction.

COLLISION THEORY. HOW REACTIONS HAPPEN Rate of reaction – How quickly a reaction happens. 1.Energy of the collision: Reactant must have enough energy.

IIIIIIIVV Reaction Rates. Collision Theory n Reaction rate depends on the collisions between reacting particles. n Successful collisions occur if the.

Some reactions occur is several sequential steps.

Reaction Mechanism The reaction mechanism is the series of elementary steps by which a chemical reaction occurs. The sum of the elementary steps must give.

Reactions rate and Collision Theory

Reaction Process.

Ch 13 Reaction Mechanisms

Lecture 1405 Reaction Mechanism and Catalysis

SECTION 1. THE REACTION PROCESS

Rates of Reactions.

Collision Theory Basic concept: reactant particles - atoms, molecules, or ions, must collide with each other to react. Number of effective collisions.

Ch. 17 – Chemical Reactions

Warm up # Label each part of the graph. A. B. C. D. E. F. G. H.

Factors Effecting Reaction Rate

IV. Reaction Energy and Rates

KINETICS Chapter 16.

DO NOW Get out Reaction Mechanism Practice. Pick up review.

CHEMICAL KINETICS.

Reaction Mechanism The reaction mechanism is the series of elementary steps by which a chemical reaction occurs. The sum of the elementary steps must give.

3.6.1 Energy During Collision

Reaction Mechanics.

How Fast Does the Reaction Go?

Kinetics Branch of chemistry that deals with the rates of chemical reactions TOPIC 8 Review Book.

Reaction Mechanism The reaction mechanism is the series of elementary steps by which a chemical reaction occurs. The sum of the elementary steps must give.

ENERGY & CHEMICAL CHANGE

Ch. 17 – Chemical Reactions

Rates of Chemical Reactions

Reaction Energy.

Reaction Mechanisms and Catalysts (p.26)

Aim: How are reaction (rxn) rates affected?

Collision theory.

DO NOW Get out homework handout Pick up notes.

Rate Affecting Factors

Unit 12: Reaction Rates & Equilibrium

IV. Reaction Energy and Rates

Unit 8: Rates of Reactions

Unit 4: Kinetics Collision Theory.

Chapter 17: Reaction Rates

Factors affecting rates of reaction

Presentation transcript:

Catalysts: Speed up reaction rates by offering an alternate reaction pathway with a lower activation energy How they work … Remember “collision theory” from yesterday 1. The reacting molecules must collide with one another 2. The reacting molecules must collide w/ sufficient energy to initiate the breaking and forming bonds 3. The molecules must collide in an orientation that can lead to the proper rearrangement of products

Catalysts: Types: 1. Surface catalysts – reacting particle attaches to catalytic surface, exposing the part of the molecule that is able to react Examples – metals (Pt, Ni, etc) 3. The molecules must collide in an orientation that can lead to the proper rearrangement of products

Catalysts: Types: 2. Enzyme catalysts– enzymes are large, biological molecules (proteins) with very specific and complex shapes 3. The molecules must collide in an orientation that can lead to the proper rearrangement of products

Catalysts: Types: 2. Enzyme catalysts– enzymes are large, biological molecules with very specific and complex shapes 3. The molecules must collide in an orientation that can lead to the proper rearrangement of products

Catalysts: Types: 3. Acid-base catalysts– look for common acids and bases (HCl, H2SO4, NaOH, NH3) 3. The molecules must collide in an orientation that can lead to the proper rearrangement of products

Reaction Mechanisms: The sequence of bond-making and bond-breaking steps of a reaction These steps are often called elementary steps A proposed mechanism is always theoretical, can not be proven

Reaction Mechanisms: Example: Br2 + 2 NO  2 BrNO Is this rxn likely to happen in 1 step? NO!!! NO 3 particles would have to collide simultaneously, in exactly the right orientation, which is very unlikely … Br2 NO

Reaction Mechanisms: Example: Br2 + 2 NO  2 BrNO Elementary Steps

Reaction Mechanisms: Example: Br2 + 2 NO  2 BrNO Elementary Steps

Reaction Mechanisms: Example: Br2 + 2 NO  2 BrNO Elementary Steps 2. Br2NO + NO  BrNO + BrNO

Reaction Mechanisms: Example: Br2 + 2 NO  2 BrNO Elementary Steps 2. Br2NO + NO  BrNO + BrNO Show that these mechanism steps give the correct net reaction.

Reaction Mechanisms: Br2 + 2 NO  2 BrNO Elementary Steps 2. Br2NO + NO  BrNO + BrNO What would the reaction coordinate diagram look like if the activation energy for the net reaction is 100 kJ and it is known to be exothermic?

Reaction Mechanisms: The decomposition of ozone … Elementary Steps 1. Cl + O3  O2 + ClO 2. ClO + O3  Cl + 2O2 What is the net reaction? ID any intermediates, catalysts, reactants and products.

Reaction Mechanisms: The decomposition of ozone … Elementary Steps 1. Cl + O3  O2 + ClO 2. ClO + O3  Cl + 2O2 A different catalyst is introduced that adds 2 steps to the proposed mechanism as represented above. Which step is the slowest?

Reaction Mechanisms: H+ + I- + H2O2  H2O + HOI Elementary Steps 1. H+ + H+ + H2O2  H4O2+2 2. Propose a second step in the mechanism

Reaction Mechanisms: H+ + I- + H2O2  H2O + HOI Elementary Steps 1. H+ + H+ + H2O2  H4O2+2 2. H4O2+2 + I-  H2O + HOI + H+ This reaction is known to be very fast. Do you agree with this proposed mechanism?

Practice On Your Own:

Practice On Your Own: