13-1 CHEM 102, Spring 2012, LA TECH CTH :00-11:15 am Instructor: Dr. Upali Siriwardane Office: CTH 311 Phone Office Hours: M,W 8:00-9:00 & 11:00-12:00 am; Tu, Th, F 8: :00am.. Exams: 10:00-11:15 am, CTH 328. September 25, 2012 (Test 1): Chapter 13 October 18, 2012 (Test 2): Chapter 14 &15 November 13, 2012 (Test 3): Chapter 16 &18 Optional Comprehensive Final Exam: November 15, 2012 : Chapters 13, 14, 15, 16, 17, and 18 Chemistry 102(001) Fall 2012

13-2 CHEM 102, Spring 2012, LA TECH Syllabus and Grading 1) Three tests 600 (60%) 2) 11 Group-Homeworks (GHW)200 (20%) 3) 20 Quizzes and attendance100 (10%) 4) 3 OWL assignments 100 (10%) 1000 (100%) 1000 (100%)Bonus 1) Bonus Assignment 40 (4%) 2) Bonus Point-class participation 10 (1%) Complete the syllabus questionnaire

13-3 CHEM 102, Spring 2012, LA TECH GHW# 1: Chapter 13 Chemical Kinetics: Reaction Rates

13-4 CHEM 102, Spring 2012, LA TECH Chapter 13. Chemical Kinetics 13.1 Reaction Rate 13.2 Effect of Concentration on Reaction Rate 13.3 Rate Law and Order of Reaction 13.4 A Nanoscale View: Elementary Reactions 13.5Temperature and Reaction Rate: The Arrhenius Equation Equation 13.6Rate Laws for Elementary Reactions 13.7Reaction Mechanisms 13.8Catalysts and Reaction Rate 13.9Enzymes: Biological Catalysts 13 ‑ 10Catalysis in Industry

13-5 CHEM 102, Spring 2012, LA TECH Why Study Rates of Reactions? 1) Rates show us how fast/slow a reaction would take place. 2) We need make some reactions go faster. 3) Some reactions needed to be slowed down. 4) We need the conceptual back ground understand the “factors” that would change the rate of a reaction 5) In this chapter we will go through models and the theories dealing with reaction rates (Chemical Kinetics)

13-6 CHEM 102, Spring 2012, LA TECH Reaction of cis-platin with Water Substitution reaction

13-7 CHEM 102, Spring 2012, LA TECH Disappearance of Color Intensity of Color is proportional to amount of reactant

13-8 CHEM 102, Spring 2012, LA TECH How do you measure rates? How do you measure rates? Rates are related to the time it required to decay reactants or form products. The rate reaction = change in concentration of reactants/products per unit time Average rate rate of reaction = –  [reactant]/  t Instantaneous rate rate of reaction = – d[reactant]/dt

13-9 CHEM 102, Spring 2012, LA TECH Measuring Reaction Rate a A --> b B Based on reactants rate = -(1/a)  [A]/  t Based on products rate = +(1/b)  [B]/  t  [A]= [A] f - [A] I Change in A  t= t f - t i Change in t

13-10 CHEM 102, Spring 2012, LA TECH Rate of Appearance & Disappearance is different from Reaction Rates 2 N 2 O 5 (g) -----> 4 NO 2 (g) + O 2 (g) Disappearance is based on reactants rate = -(  [N 2 O 5 ]/  t Appearance is based on products rate =  [NO 2 ]/  t rate =  [O 2 ]/  t Converting rates of Appearance. rate = (  [NO 2 ]/  t = - 4/2  [N 2 O 5 ]/  t  [O 2 ]/  t = - 1/2  [N 2 O 5 ]/  t

13-11 CHEM 102, Spring 2012, LA TECH 1) What is the rate of a chemical reaction? (Describe in your own words and then in equation) a A ----> b B + c C a A ----> b B + c C

13-12 CHEM 102, Spring 2012, LA TECH 2) Answer the following Given the chemical reaction: 2 N 2 O > 4 NO 2 + O 2 a) What’s the rate of disappearance ( or decomposition) N 2 O 5 ? (Equation) b) What are the rates of appearance of NO 2 and O 2 ? (Equations)

13-13 CHEM 102, Spring 2012, LA TECH 2) Answer the following Given the chemical reaction: 2 N 2 O > 4 NO 2 + O 2 c) What are the rates of reaction based on N 2 O 5, NO 2, and O 2 ? (Equations) d) Are the rates of decomposition based on N2O5, and formation based on, NO 2, and O 2 equal? (Explanation)

13-14 CHEM 102, Spring 2012, LA TECH 2) Answer the following Given the chemical reaction: 2 N 2 O > 4 NO 2 + O 2 e) Are the rate of reaction based on N 2 O 5, NO 2, and O 2 equal? (Equations and explanation)

13-15 CHEM 102, Spring 2012, LA TECH 2) Answer the following Given the chemical reaction: 2 N 2 O > 4 NO 2 + O 2 e) Are the rate of reaction based on N 2 O 5, NO 2, and O 2 equal? (Equations and explanation)

13-16 CHEM 102, Spring 2012, LA TECH 3) What are the differences between average and instantaneous reaction rates? Refer to graph in new concepts. 4) Why is instantaneous rates of N 2 O 5 and NO 2 are negative and positive respectively?

13-17 CHEM 102, Spring 2012, LA TECH 2 N 2 O 5 (g) -----> 4 NO 2 (g) + O 2 ( g) Graphing Kinetics Data Average rate =

13-18 CHEM 102, Spring 2012, LA TECH Graph of 2 N 2 O 5 (g) ---> 4 NO 2 (g) + O 2 (g)

13-19 CHEM 102, Spring 2012, LA TECH 3) What are the differences between average and instantaneous reaction rates? Refer to graph in new concepts. 4) Why is instantaneous rates of N 2 O 5 and NO 2 are negative and positive respectively?

13-20 CHEM 102, Spring 2012, LA TECH Graph

13-21 CHEM 102, Spring 2012, LA TECH Graph in Problem 7 Time / min [N 2 O 5 ] / moldm ) At what time the reaction is complete?

13-22 CHEM 102, Spring 2012, LA TECH Graph in Problem 7 6) Plot this data using excel and attach the graph and do the calculations using the spread sheet: What are the rates of reaction between following min intervals? 0-20 = 2.06 x mol dm -3 min = = =

13-23 CHEM 102, Spring 2012, LA TECH 7) How does reaction rate vary with time in the graph? Consider the decomposition of N 2 O 5.

13-24 CHEM 102, Spring 2012, LA TECH 8)What are the main factors that affect a rate of a chemical reaction?

13-25 CHEM 102, Spring 2012, LA TECH a) Temperature b) Concentration c) Catalysts d) Particle size of solid reactants Factors that affect rates of chemical reactions

13-26 CHEM 102, Spring 2012, LA TECH Effect of Particle Size on Rate

13-27 CHEM 102, Spring 2012, LA TECH 9) In the graph below, what are the main features regarding rates based on reactants and products and their stoichiometric coefficients and what does it mean by kinetic and equilibrium regions?