Chem Final Exam Review

Chem Final Exam Review - Chem Final Exam Review Exam 2-...

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Chem Final Exam Review Exam 2- Chapter 13 and 9 Rate is ratio of quantity change over a period of time o Ratio is time involved for reactants to be used and products to be formed Chemical kinetics o Rate of reaction (M/time) You can calculate the rate of disappearance/appearance of a product/reactant, and use that rate to calculate the overall rate of reaction. Just multiply the rate of that product/reactant by its inverse stoichiometric ratio. o Factors that affect reaction rate Nature of reactants Physical state- gases react more violently than solids or liquids Allotropes- some natural forms react differently Solid vs aqueous- aqueous reacts more Solid vs powdered- increasing surface area increases reaction rate. Group 1 metals have low IE and react rapidly with water Group 2 metals have higher E and react slower with water Concentration of reactants Rate law expression relates concentration and rate o Rate= k [A] x [B] y [C] z (k is a constant for a reaction at particular temperature and depends on the overall reaction order, and catalyst, not on the concentration of reactants or products ) x,y,z are determined experimentally o When determining the order, you can compare two different rates to two differ Integrated rate equation relates concentration and time o First order: ln [Ao]/[A] = akt [A]= .5[Ao] at .5t (for first order only, half-life of a reactant does not depend on initial concentration of A. .5t=.693/a o Second order: 1/[A] – 1/[Ao] = akt .5t= 1/ ak[Ao] o Zero order: [A] = [Ao] – akt .5t= [Ao]/2ak Collision theory o Effective collisions require a minimum amount of energy to break and form new bonds during collision o Effective collisions must be properly oriented during the time of collision Transition State Theory o Reactants pass through short-lived high-energy intermediate states, or transition states. Activation nrg forward- nrg needed to reach the transitional state Activation nrg reverse- nrg to reach transition state in reverse Net nrg release- nrg released when reactants go from transition state to product Temperature Average kinetic energy is directly proportional to absolute temperature o An increase in temperature causes an increase in kinetic energy which allows more molecules the kinetic energy to reach the transition state
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This note was uploaded on 04/30/2008 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas at Austin.

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Chem Final Exam Review - Chem Final Exam Review Exam 2-...

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