Ch-141516-TTK-Brown

# Ch-141516-TTK-Brown - Chapter 14 - Things to Know 14.1 What...

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1 Chapter 14 - Things to Know 14.1 What factors can affect the rate of a reaction? 14.2 Rates of reaction: units used, average vs. instantaneous rate, how to calculate each using a graph of concentration vs. time. Relating the “overall” rate of the reaction to rates of change of reactants and products, using a balanced equation. Understand the meaning and be able to write the mathematical expressions. How does the rate change as time goes on? 14.3 Rate law: form of rate law (Rate = k[A] x [B] y ), order of reaction, rate constant, overall order. What does a rate law tell you? How can you determine the rate law experimentally? (know two ways) Is there any other way of determining a rate law? Method of initial rates: determine rate law, calculate k. What is the logic? 14.4 Concentration-time equations: zero, first, and second order. Know how to tell the equations apart, be able to do the algebra! (Given any 3 pieces of information, calculate the 4th) What are the units of k? (Depends on overall reaction order) Graphing: for each order (0, 1, or 2), what do you graph in order to get a straight line? How do you determine the rate constant from the graph? Half-life: what is it? Useful for first order reactions - why? How is it determined? How does it give you a shortcut in certain situations? 14.5 Collision Theory - what must happen for a reaction to occur? What is E a ? How does E a correspond to the rate of a reaction? Why ? Explain at the molecular level how changing concentrations or changing temperature affect the rate of reaction. How does the # molecules vs. kinetic energy diagram fit in? Transition State Theory - what is a transition state? Understand potential energy diagrams, label/determine H, E a (forward) and E a (reverse). Arrhenius equation: relates rate constants at different temperatures, and includes E a . Know how to do calculations with the two-point form of the equation. A graph of ln k vs. 1/T is linear (for any reaction order). How do you determine E a from the graph? Be able to do this. 14.6 What is a mechanism? What is an elementary reaction? Why can you write the rate law for an elementary reaction without any other information? Why can't you normally write the rate law from a balanced equation? Molecularity, Rate-determining step (slowest) Getting the rate law from a mechanism: two types we'll do. 1. Initial slow step (easy)

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2 2. Initial fast, equilibrium step (can't include intermediates in the overall rate law, so you have to make a substitution) Intermediate vs. catalyst 14.7 What does a catalyst do? How? Explain why lowering the activation energy leads to a faster rate of reaction. Chapter 15 - Things to Know 15.1 What does it mean if a system is at equilibrium? What's going on? Anything? What is "equal"? (NOT the concentrations!) 15.2, Writing K c , K p , K eq expressions. Don't include liquids or solids in K expressions.
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## This note was uploaded on 09/04/2011 for the course CHEM 1B taught by Professor Fossum during the Spring '10 term at Laney College.

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Ch-141516-TTK-Brown - Chapter 14 - Things to Know 14.1 What...

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