# UGA CHEM 1212 - Reaction Rates (3 pages)

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## Reaction Rates

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Explains what rates of reactions depend on

- Lecture number:
- 7
- Pages:
- 3
- Type:
- Lecture Note
- School:
- University of Georgia
- Course:
- Chem 1212 - Freshman Chem Ii

**Unformatted text preview: **

CHEM 1212 1nd Edition Lecture 7 Outline of Last Lecture I Rates of Chemical Reactions II Reaction Conditions and Rate III Effects of Concentration on Reaction Rates IV Rate Equations V The Order of a Reaction VI The Rate Constant k VII Determining a Rate Equation Outline of Current Lecture I Concentration II Collision Theory III The Arrhenius Equation IV Effects of Catalysts on Reaction Rates Current Lecture I Concentration Time Relationships Integrated Rate Laws a Equations used to calculate the concentrations of reactions and products after an elapsed period of time b First order reactions i Integrated rate equation ln R 2 kt R 0 ii The R s in this equation are the concentrations of the reactants at time t 0 and at a later time iii Calculations where this would be used These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 1 If R 2 R 0 is measured in the laboratory after some amount of time has elapsed then k can be calculated 2 If R 0 and k are known then the concentration of material remaining after a given amount of time R t can be calculated 3 If k is known then the time elapsed until a specific fraction R t R 0 remains can be calculated c Second order reactions i Rate equation 1 1 kt R t R 0 d Zero order reactions i Rate equation R 0 R t kt ii Units of k are mol L x s e Graphical methods for determining reaction order and the rate constant i Rate equations if rearranged have the form y mx b f Half Life and First Order Reactions i The half life t1 2 of a reaction is the time required for the concentration of a reaction to decrease to one half its initial value ii The longer the half life the slower the reaction iii Usually used when dealing with first order reactions iv The half life is the time when R t R 0 v In order to find the half life we substitute in the as the concentration fraction and replace t with t1 2 vi For first order reaction half life t1 2 0 693 K

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