CHAPTER 13 - CHAPTER 13-13.6 13.1 CATCHING LIZARDS *to...

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CHAPTER 13-13.6 13.1 CATCHING LIZARDS *to catch liz pour ice cold water on top of them immobilizes them catch them n put in sand and leaves warms up and becomes active *immobilizes ^ them b/c its movement depends on chemical reaction that occur with its muscle and the rates of those reactions—how fast they occur—highly sens to temp *temp goes down, the reaction that produces movement occur more slowly movement itself slows down *unlike mammals (actively regulate their body temp through metabolic activity, lizards are ECTOTHERMS—body temp depends on their surroundings *1 st person to measure rate of a chemical reaction carefully Ludwig Wilhelmy 1850, measured how fast sucrose (with acid) hydrolyzes into glucose and fructose 13.2 THE RATE OF A CHEMICAL REACTION (measure of how fast the reaction occurs) *if reaction has slow rate only small fraction of molecules react to form products in a given time *if high rate more fraction of molecules react to form products in a given time *measure rate as a change in some quantity per unit of time (i.e. m/s) *the rate of a chemical reaction in measured as a change in the amts of reactants or products (usually in terms of concentration) divided by the change in time *reaction rate is defined as the negative of the change in cencentration of a reactant divided by the change in time negative because reactant concentration decreases as a reaction proceeds; therefore the change in the concentration of a reactant is negative *because product concentration increases as the reaction proceeds, the change in concentration of a product is positive—when the rate is define with respect to a product, we do not include a negative sign in the definition look at graph on page 572 CHANGE IN REACTANT AND PRODUCT CONCENTRATIONS *reactant concen decreases with time because reactants are consumed in a reaction *product concen increases with time because products are formed in a reaction *the increase in HI concentration occurs at exactly twice the rate of the decrease in H2, b/ c of the Stoichiometry of the reaction—2 mol of HI is formed for every 1 mol of H2 consumed
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THE AVERAGE RATE OF THE REACTION *average rate of reaction can be calculated for any time using - delta H/ delta time *average rate (with respect to reactants) decreases as the reaction progresses *reaction slows down as it proceed *rate depends on the concentrations of reactants
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This note was uploaded on 05/05/2009 for the course CHEMISTRY CHEM142 taught by Professor Metcalf during the Spring '09 term at UVA.

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CHAPTER 13 - CHAPTER 13-13.6 13.1 CATCHING LIZARDS *to...

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