#Chem 162-2008 4th week recitation

# #Chem 162-2008 4th week recitation - CHEMISTRY 162-2008 4th...

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CHEMISTRY 162-2008 4 th WEEK RECITATION ANNOUNCEMENTS E-MAIL ATTENDANCE Sign in EXAMS    1 st  hourly: Wed., Feb. 20 th , 9:40-11:00 PM.    Review session: Thursday, Feb. 14 th , 8:00-10:00 PM, CDL 102 Chapter 12 - Solutions Sunday, Feb. 17 th , 8:30-10:30 PM, Hck 138 Chapter 13 - Kinetics QUIZ Lect. and rec. quizzes graded; pick-up after class. Hold onto all quizzes until end of semester. Chem 162-2008 4th week recitation 1

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PLAN FOR TODAY : CHAPTER 13 (cont.) - CHEMICAL KINETICS Temperature dependence of rate constant (Arrhenius equation) Reaction mechanisms CHAPTER 14 – CHEMICAL EQUILIBRIUM* The equilibrium constant Equilibrium calculations * Easy, but extremely important; basics for chapters 14, 15 & 16 Chem 162-2008 4th week recitation 2
FORMULAS C 12 H 22 O 11 + H 2 O ----> C 6 H 12 O 6 + C 6 H 12 O 6 Rate of sucrose disappearance = -(∆ [sucrose])/(∆ time) = -([sucrose f ] – [sucrose i ])/(t f – t i ) aA + bB ----> cC + dD General rate of reaction = -(1/a)(∆[A]/∆t) = -(1/b)(∆[B]/∆t) = (1/c)(∆[C]/∆t) = (1/d)(∆[D]/∆t) Determination of order of reaction through method of initial rates: For a single reactant: Rate 1 = k[A 1 ] m Rate 2 = k[A 2 ] m (Rate 1/Rate 2) = (k[A 1 ] m )/(k[A 2 ] m ) = ([A 1 ]/[A 2 ]) m For two reactants: Rate1 = k[A 1 ] m [B 1 ] n Rate2 = k[A 2 ] m [B 1 ] n (Rate1/Rate2) = (k[A 1 ] m [B 1 ] n )/(k[A 2 ] m [B 1 ] n ) = (A 1 /A 2 ) m Integrated Reaction Differentiated rate law k Order Reaction Rate** RATE LAW*** (y = mx + b) Half-life * units 0 Rate = -(C 2 -C 1 )/(t 2 -t 1 ) Rate = k[C] o =k [C] t = -kt + [C] o t 1/2 = [C] o /2k M 1 s -1 1 Rate = -(C 2 -C 1 )/(t 2 -t 1 ) Rate = k[C] 1 ln[C] t = -kt + ln[C] o t 1/2 = 0.693/k M o s -1 2 Rate = -(C 2 -C 1 )/(t 2 -t 1 ) Rate = k[C] 2 1/[C] t = kt + 1/[C] o t 1/2 = 1/(k[C] o ) M -1 s -1 ** Rate of appearance = +slope; rate of disappearance = -rate of appearance = -slope. *** Differentiated Rate Law may be for more than one component, e.g., Rate = k[C] 1 [D] 2 *Half-lives : For a zero order reaction, each successive half-life is ½ the preceding one. For a first order reaction, each successive half-life is equal to the preceding one. For a second order reaction, each successive half-life is double the preceding one. Arrhenius equation: k = Ae (-Ea/RT) ; ln k = ((-E a /R) x (1/T)) + ln A A = frequency factor = combination of steric factor and collisional frequency E a = energy of activation ln k 2 – ln k 1 = (-E a /RT 2 ) – (-E a /RT 1 ) Chem 162-2008 4th week recitation 3 ln k = -E a /RT + ln A ln (k 2 /k 1 ) = -(E a /R)[(1/T 2 ) - (1/T 1 )]

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COLLISION THEORY, INCLUDING ARRHENIUS EQUATION ET: What factors affect the reaction rate? Rate = k[A] m [B] n . Concentration of reactants, reaction order and k affect the rate. ET: Draw curve showing that higher concentration = higher rate. ET: What affects the rate constant? Qualitatively: Collision Theory is built around the central idea that for molecules to react they must (1) collide, (2) have the right energy, (3) have the right geometry. ET: What affects the rate constant? Quantitatively: Arrhenius equation. Discuss Ea.
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## This note was uploaded on 09/23/2009 for the course CHEM 162 taught by Professor Siegal during the Spring '08 term at Rutgers.

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#Chem 162-2008 4th week recitation - CHEMISTRY 162-2008 4th...

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