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Chemistry 102(01) Fall 2013

Chemistry 102(01) Fall 2013. Instructor: Dr. Upali Siriwardane e-mail : upali@coes.latech.edu Office : CTH 311 Phone 257-4941 Office Hours : M,W 8:00-9:30 & 11:00-12:30 am; Tu,Th , F 8:00 - 10:00 am ., or by appointment.  Test Dates :.

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Chemistry 102(01) Fall 2013

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  1. Chemistry 102(01) Fall 2013 Instructor: Dr. UpaliSiriwardane e-mail: upali@coes.latech.edu Office: CTH 311 Phone257-4941 Office Hours: M,W 8:00-9:30 & 11:00-12:30 am; Tu,Th, F 8:00 - 10:00 am., or by appointment.  Test Dates: September 24, 2013 (Test 1): Chapter 13 October 17, 2013 (Test 2): Chapter 14 &15 November 12, 2013 (Test 3) Chapter 16 &17 November 14, 2013 (Make-up test) comprehensive: Chapters 13-17 10:00-11:15 am., CTH 328

  2. Chapter 13. Chemical Kinetics 13.1 Catching Lizards 563 13.2 The Rate of a Chemical Reaction 564 13.3 The Rate Law: The Effect of Concentration on Reaction Rate 569 13.4 The Integrated Rate Law: The Dependence of Concentration on Time 573 13.5 The Effect of Temperature on Reaction Rate 581 13.6 Reaction Mechanisms 588 13.7 Catalysis 593

  3. Why Study Rates of Reactions? • Rates show us how fast/slow a reaction would take place. • We need make some reactions go faster. • Some reactions needed to be slowed down. • We need the conceptual back ground of the “factors” that would change the rate of a reaction • In this chapter we will go through models and the theories dealing with reaction rates (Chemical Kinetics)

  4. 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 = –D[reactant]/Dt Instantaneous rate rate of reaction = –d[reactant]/dt H2 + I2 --> 2 HI

  5. Reaction of cis-platin with Water Substitution reaction

  6. Disappearance of Color Intensity of Color is proportional to amount of reactant

  7. Rate of Appearance & Disappearance is different from Reaction Rates • 2 N2O5(g) -----> 4 NO2 (g) + O2 (g) • Disappearance is based on reactants • rate = -(D[N2O5]/ D t • Appearance is based on products • rate = D[NO2]/ D t • rate = D[O2]/ D t • Converting rates of Appearance and disapperence. • rate = (D[NO2]/ D t = - 4/2 D[N2O5]/ D t • D[O2]/ D t = - 1/2 D[N2O5]/ D t

  8. Measuring Reaction Rate a A --> b B Based on reactants rate = -(1/a) D[A]/ D t Based on products rate = +(1/b) D[B]/ D t D[A]= [A]f - [A]I Change in A D t= tf - ti Change in t

  9. 1) What is the rate of a chemical reaction? (Describe in your own words and then in equation) • a A ----> b B + c C

  10. 2) Answer the following Given the chemical reaction: • 2 N2O5 ----> 4 NO2 + O2 • What’s the rate of disappearance ( or decomposition) N2O5? (Equation) • b) What are the rates of appearance of NO2 and O2? (Equations)

  11. 2) Answer the following Given the chemical reaction: • 2 N2O5 ----> 4 NO2 + O2 • c) What are the rates of reaction based on N2O5, NO2 , and O2? (Equations) • d) Are the rates of decomposition based on N2O5, and formation based on , NO2 , and O2 equal? (Explanation)

  12. 2) Answer the following Given the chemical reaction: • 2 N2O5 ----> 4 NO2 + O2 • e) Are the rate of reaction based on N2O5, NO2 , and O2 equal? (Equations and explanation)

  13. 2) Answer the following Given the chemical reaction: • 2 N2O5 ----> 4 NO2 + O2 • e) Are the rate of reaction based on N2O5, NO2 , and O2 equal? (Equations and explanation)

  14. 3) What are the differences between average and instantaneous reaction rates? Refer to graph in new concepts. • 4) Why is instantaneous rates of N2O5 and NO2 are negative and positive respectively?

  15. 3) What are the differences between average and instantaneous reaction rates? Refer to graph in new concepts.

  16. 4) Why is instantaneous rates of N2O5 and NO2 are negative and positive respectively?

  17. 2 N2O5(g) -----> 4 NO2 (g) + O2 (g) Graphing Kinetics Data Average rate =

  18. Graph

  19. Graph in Problem 7 • 5) At what time the reaction is complete?

  20. 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 = - ½ [N2O5]f - [N2O5]i = 2.06 x 10-4mol dm-3min-1 • tf - ti • 0-20 = - ½ [0.00933] - [0.01756] = 2.06 x 10-4mol dm-3min-1 • 20 - 0 • 20-40 = • 40-60 = • 60-80 =

  21. 7) How does reaction rate vary with time in the graph? Consider the decomposition of N2O5.

  22. Factors that affect rates of a chemical reactions • a) Temperature • b) Concentration • c) Catalysts • d) Particle size of solid reactants

  23. 8) What are the main factors that affect a rate of a chemical reaction?

  24. Effect of Particle Size on Rate

  25. 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?

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