CHEM 1120 Edition 1nd Lecture 4 Outline of Last Lecture I Colligative Properties Continued from Last Lecture a Vapor Pressure lowering continued b Boiling Point Elevation and Freezing Point Depression c Osmosis II Colligative Properties of Electrolyte solutions a Dependent on number of ions III Colloids a What they are b Tyndall Effect c Hydrophilic and Hydrophobic colloids IV Begin Chapter 14 Intro to chapter Outline of Current Lecture I Chapter Intro II Reaction Rates a 1 a A t 1 b B t 1 c C t 1 d D t III Concentration and Rate a Rate Law k x A m x B n b What factors affect speed of reaction 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 i ii iii iv Reactant physical state Reactant concentration Temperature Catalysts c Average Rate vs Instantaneous Rate d Units of Rate Constants Current Lecture I II III Chapter Intro a How fast are chemical reactions i Rusting very slow ii Combustion very fast iii Cooking eggs in between b Why do we care Want to manipulate speed Reaction rates a Mathematically i 1 a A t 1 b B t 1 c C t 1 d D t ii Where reaction is aA bB cC dD iii change in concentration iv t change in time v a b c d stoichiometric coefficients vi Measured in units of concentration per unit time i e M s Concentration and Rate a Rate of chemical reaction usually depends on concentration b Rate law works in most cases i Rate k x A m x B n ii Where reaction is aA bB cC dD iii K rate constant depends on temperature iv m is the order of the reaction with respect to A v n is the order of the reaction with respect to B vi m n is the overall reaction order vii m and n are usually integers viii m and n do not have to be equal to a and b but they usually are ix rate is constantly changing because concentrations are constantly changing c What factors affect the speed of a reaction i Reactant physical state 1 i e fine powder vs solid block ii Reactant concentration 1 i e Dilute acid vs concentrated acid iii Temperature 1 i e boiling an egg iv Catalysts 1 i e automobile catalytic converter d Average Rate vs Instantaneous rate i Average rate 1 A final A initial t final t initial A t 2 Rate of reaction averaged over a period of time ii Instantaneous rate slope of the tangent line to the curve rate at an arbitrarily short time 1 Rate of reaction at a particular point in time iii Initial rate slope near time 0 e Units of Rate constants i Units of rate units of rate constant Units of concentration order
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