CHEM 1120 1nd Edition Lecture 4 Outline of Last Lecture I. Colligative Properties Continued from Last Lecturea. Vapor Pressure lowering continuedb. Boiling Point Elevation and Freezing Point Depressionc. OsmosisII. Colligative Properties of Electrolyte solutionsa. Dependent on number of ionsIII. Colloidsa. What they areb. Tyndall Effectc. Hydrophilic and Hydrophobic colloidsIV. Begin Chapter 14-Intro to chapterOutline of Current Lecture I. Chapter IntroII. Reaction Ratesa. –1/a(ΔA/Δt) = -1/b (ΔB/Δt) = 1/c (ΔC/Δt) = 1/d (ΔD/Δt)III. Concentration and Ratea. Rate Law: k x [A]^m x [B]^nb. What factors affect speed of reactionThese 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. Reactant physical stateii. Reactant concentrationiii. Temperatureiv. Catalystsc. Average Rate vs Instantaneous Rated. Units of Rate ConstantsCurrent LectureI. Chapter Introa. How fast are chemical reactionsi. Rusting=very slowii. Combustion=very fastiii. Cooking eggs=in betweenb. Why do we care? Want to manipulate speedII. Reaction ratesa. Mathematicallyi. –1/a(ΔA/Δt) = -1/b (ΔB/Δt) = 1/c (ΔC/Δt) = 1/d (ΔD/Δt)ii. Where reaction is aA + bB cC + dDiii. Δ[ ] = change in concentrationiv. Δt = change in timev. a, b, c, d = stoichiometric coefficientsvi. Measured in units of concentration per unit time (i.e. M/s)III. Concentration and Ratea. Rate of chemical reaction usually depends on concentrationb. Rate law (works in most cases)i. Rate = k x [A]^m x [B]^nii. Where reaction is aA + bB cC + dDiii. K = rate constant, depends on temperatureiv. m is the order of the reaction with respect to Av. n is the order of the reaction with respect to Bvi. m + n is the overall reaction ordervii. m and n are usually integersviii. 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 changingc. What factors affect the speed of a reactioni. Reactant physical state1. i.e. fine powder vs solid blockii. Reactant concentration1. i.e. Dilute acid vs concentrated acidiii. Temperature1. i.e. boiling an eggiv. Catalysts1. i.e. automobile catalytic converterd. Average Rate vs. Instantaneous ratei. Average rate1. [A] final – [A] initial / t final – t initial = Δ [A]/ Δt2. Rate of reaction averaged over a period of timeii. Instantaneous rate: slope of the tangent line to the curve, rate at an arbitrarily short time1. Rate of reaction at a particular point in timeiii. Initial rate: slope near time=0e. Units of Rate constantsi. Units of rate = (units of rate constant)(Units of
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