CHM 104 1st Edition Lecture 2 Outline of Last Lecture I Math Review and Syllabus Outline of Current Lecture II Chemical Kinetics and Rate III Rate of Change of Chemical Concentration Current Lecture Chapter 13 Chemical Kinetics The study of CHEMICAL CHANGE with time to determine HOW a reaction occurs How to characterize the speed rate at which chemical change occurs Over time the reactant concentration decreases and the product concentration increases reactant decreases and product increases This symbol means concentration Based on 1 1 stoichiometry we can determine s at all times 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 0 0200 0 0180 Changing Concentration M 0 0160 0 0140 0 0120 0 0100 0 0080 MI ACN 10000 12000 0 0060 0 0040 0 0020 0 0000 0 2000 4000 6000 8000 14000 Time s From the graph we can see that reactant decreases fast initially and then slows down and the product increases fast initially and then slows down The lines on our chart mirror each other Rate of Change of chemical concentrations measured over a specific time and interval change Concentration Something final state of something initial state of same something Concentration t2 t1t2 time 2 t1 time 1 Units M s Example 0 2000 s Reactant Product What is the rate of the reaction By convension Rate of reaction is always expressed as a positive number Convension unit of M s Molarity per second Example H2 g I2 g 2 HI g We can define the RATE that this reaction proceeds in terms of H 2 1 I2 HI Reaction produces 2 HI molecules for every 1 H2 and 1 I2 molecule consumed Rate of formation of HI is TWICE the rate of H2 and I2 consumed In order to have a single number for reaction rate the definition of reaction rate must take into account STOICHIOMETRIC coefficients IN GENERAL aA bB cC dD
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