Chpt 12 Lec - Chapter 12: Chemical Kinetics 1 Chemistry 8/e...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 12: Chemical Kinetics 1 Chemistry 8/e Steven S. Zumdahl and Susan A. Zumdahl Chapter Contents Introduction Rates of Reactions Differential Reaction Rate Laws Experimental Determinations Integrated Rate Laws th Order 1 st Order & Life 2 nd Order Multiple Reactants Reaction Mechanisms Models for Kinetics Catalysis 2 Three most basic questions of chemistry: will something react, if they do what will you get and how fast will it go. This is about how fast will it go KINETICS 3 Kinetics of processes have appeared before: Kinetic Theory has been invoked several times. In the origin of pressure As van der Waals pressure correction As a justification for Raoults Law In the development of the Mass Action Law 4 Kinetics The speed with which chemical reactions proceed is governed by two things: The rate at which reactants come into one anothers proximity (collide) and The probability that any given collision will prove effective in turning reactants to products. We look first at the macroscopic measurement of reaction rates. 5 Kinetics Change of Concentration in Time Reactants vanish in time, so [reactant] is a falling function of t . Likewise [product] is a rising function of t . The shape of these functions tells us about concentration dependence. 6 Time Concentration A B [A] [A] [B] t Representation of the Reaction of 2NO 2 (g) 2NO(g) + O 2 (g) 7 t=0 Concentrations change during a reaction: [reactants] goes down [products] goes up Rate is how fast they go up or down. 8 The rate is dependent on concentration. Here, rate = - [NO 2 ]/ t Or, Rate = [NO]/ t Or Rate = [O 2 ]/ t 9 The rate is dependent on concentration. In general, rate is proportional to concentrations taken to some power For example, here - [NO 2 ]/ t = k[NO 2 ] n Called the rate law. k is called the rate constant, and its value can vary depending on how the rate is defined. 10 Ask the question the other way around: At t > 0 are there additional complications? Sure! At the very least, the reverse reaction of products to produce reactants changes the rate of loss of A. 11 Simplified Rate Laws Not laws like Laws of Thermodynamics but rather rate rules for simple reactions. Two versions of the Rate Laws: Differential like d[A] / dt = k [A] n Integral like [A] 1 n = [A] 1 n + (n 1) kt But they must be consistent for the same reaction. Rate exponents are often not stoichiometric. 12 Simplified INITIAL Rate Laws Since products are absent at t=0, such laws include only rate dependence on reactants....
View Full Document

This note was uploaded on 10/27/2010 for the course CHEM 104 taught by Professor Quigley during the Summer '08 term at CUNY Hunter.

Page1 / 74

Chpt 12 Lec - Chapter 12: Chemical Kinetics 1 Chemistry 8/e...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online