Modern Chemistry Chapter 17 Homework 17 2

Presentation on theme: "Chapter 17 Section 2 Reaction Rate p. 568-579 1 Reaction Kinetics Chapter 17 Modern Chemistry Sections 1 & 2 The Reaction Process Reaction Rate."— Presentation transcript:

1 Chapter 17 Section 2 Reaction Rate p. 568-579 1 Reaction Kinetics Chapter 17 Modern Chemistry Sections 1 & 2 The Reaction Process Reaction Rate

2 Chapter 17 Section 2 Reaction Rate p. 568-579 2 Reaction Rate Section 17.2

3 Chapter 17 Section 2 Reaction Rate p. 568-579 3 Chemical Kinetics: The area of chemistry that is concerned with reaction rates and reaction mechanisms. The change in concentration of a reactant (or a product) per unit time as a reaction proceeds is called the reaction rate. Rate of Reaction -  [reactant a]  time  [product b]  time or

4 Chapter 17 Section 2 Reaction Rate p. 568-579 4 Any change in reaction conditions that affects the collision frequency, the collision efficiency, or the collision energy affects the reaction rate. IF COLLISIONS ARE INCREASE, THE RATE WILL INCREASE. Rate of Reaction

5 Chapter 17 Section 2 Reaction Rate p. 568-579 5  Nature of Reactants  Temperature  Surface Area  Concentration  Catalyst Rate Influencing Factors

6 Chapter 17 Section 2 Reaction Rate p. 568-579 6 An increase in temperature increases the average kinetic energy of the particles. This increases the number of collisions and the energy of collision. To be effective, the energy of the collisions must be equal to or greater than the activation energy. At higher temperatures, more particles possess enough energy to form the activated complex.Temperature

7 Chapter 17 Section 2 Reaction Rate p. 568-579 7 Plop, Plop Fizz, Fizz

8 Chapter 17 Section 2 Reaction Rate p. 568-579 8 Breaking and making bonds cause a reaction. So…. Reaction rate is dependant on the type of bond and the molecule it’s in. It cannot be adjusted to improve reaction rate. Nature of Reactants

9 Chapter 17 Section 2 Reaction Rate p. 568-579 9 In heterogeneous reactions, the reaction rate depends on the area of contact of the reaction substances. An increase in surface area, increases the rate of heterogeneous reactions. Surface Area

10 Chapter 17 Section 2 Reaction Rate p. 568-579 10 To increase surface area, break the substance up into smaller pieces. Surface Area

11 Chapter 17 Section 2 Reaction Rate p. 568-579 11 Lycopodium Powder Explosion

12 Chapter 17 Section 2 Reaction Rate p. 568-579 12 Increasing the concentration increases the number of collisions. As the number of molecules in the system increases, so does the total number of possible collisions between them. If the number of effective collisions increases, the rate increases.Concentration

13 Chapter 17 Section 2 Reaction Rate p. 568-579 13 Gummy Bear Sacrifice http://www.woodrow.org/teachers/chemistry/institutes/1988/gummybear.htm

14 Chapter 17 Section 2 Reaction Rate p. 568-579 14 Catalysts

15 Chapter 17 Section 2 Reaction Rate p. 568-579 15 A catalyst is a substance that changes the rate of a chemical reaction without itself being permanently consumed. How a Catalyst Works provides an alternative energy pathway or reaction mechanism may form an alternative activated complex that requires a lower activation energyCatalyst

16 Chapter 17 Section 2 Reaction Rate p. 568-579 16 p. 571 H 2 O 2 Catalysts notes

17 Chapter 17 Section 2 Reaction Rate p. 568-579 17 A catalyst is not included as a reactant or product – it is written above the arrow. Two Types of Catalysts Homogeneous Catalyst- A catalyst that is in the same phase as all the reactants and products in a reaction system. Heterogeneous Catalyst – A catalyst in a different form than that of the reactantsCatalyst

18 Chapter 17 Section 2 Reaction Rate p. 568-579 18 Types of Catalyst

19 Chapter 17 Section 2 Reaction Rate p. 568-579 19 The Heterogeneous Catalytic Decomposition of Acetone

20 Chapter 17 Section 2 Reaction Rate p. 568-579 20 Ch 17 Sec 2 Homework Ch 17 Review Sheet

21 Chapter 17 Section 2 Reaction Rate p. 568-579 21 Ch 17 Sec 2 Homework Prepare for Rate of a Chemical Reaction Lab on page 586

22 Chapter 17 Section 2 Reaction Rate p. 568-579 22 Movies Insert Holt: Visualizing Matter Disc 2 TEMPERATURESURFACE AREA DECREASING RATE CONTACT OF REACTANTS CONCENTRATION

Presentation on theme: "Reaction Kinetics Chapter 17 Modern Chemistry"— Presentation transcript:

1 Reaction Kinetics Chapter 17 Modern Chemistry
Sections 1 & 2The Reaction ProcessReaction RateChapter 17 Section 1 The Reaction Process p

2 Chapter 17 Section 1 The Reaction Process p. 560-567

3 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismsH2 (g) + I2 (g)  2HI (g)This balanced equations doesn’t show the steps of this reaction.The step-by-step sequence of reactions by which the overall chemical change occurs is a Reaction Mechanism.Chapter 17 Section 1 The Reaction Process p

4 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismsH2 (g) + I2 (g)  2HI (g)Only the net chemical change is directly observable for most chemical reactions.Even a reaction that appears from its balanced equation to be a simple process may actually be the result of several simple stepsChapter 17 Section 1 The Reaction Process p

5 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismsH2 (g) + I2 (g)  2HI (g)Step 1: I2 ↔ 2IStep 2: 2I + H2 ↔ 2HII2 + H2 ↔ 2HI2I is not in the final equationChapter 17 Section 1 The Reaction Process p

6 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismsH2 (g) + I2 (g)  2HI (g)Step 1: I2 ↔ 2IStep 2: 2I + H2 ↔ 2HII2 + H2 ↔ 2HISpecies that appear in some steps but not in the net equation are known as intermediates.Chapter 17 Section 1 The Reaction Process p

7 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismsH2 (g) + I2 (g)  2HI (g)Step 1: I2 2IStep 2: I + H2 ↔H2IStep 3: H2I + I ↔2HII2 + H2 ↔2HIHomogeneous reaction, a reaction whose reactants and products exist in a single phase.Chapter 17 Section 1 The Reaction Process p

8 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismsH2 (g) + I2 (g)  2HI (g)Step 1: I2 2IStep 2: I + H2 ↔H2IStep 3: H2I + I ↔2HII2 + H2 ↔2HIChapter 17 Section 1 The Reaction Process p

9 Chapter 17 Section 1 The Reaction Process p. 560-567
Reaction MechanismChapter 17 Section 1 The Reaction Process p

10 Chapter 17 Section 1 The Reaction Process p. 560-567
Rate Determining StepChapter 17 Section 1 The Reaction Process p

11 Chapter 17 Section 1 The Reaction Process p. 560-567
Collision TheoryIn order for reactions to occur between substances, their particles must collide.The particles must collide with the CORRECT ORIENTATION and with SUFFICIENT ENERGY to break the bonds.Chapter 17 Section 1 The Reaction Process p

12 Chapter 17 Section 1 The Reaction Process p. 560-567
3 Possible CollisionsChapter 17 Section 1 The Reaction Process pp. 563

13 Chapter 17 Section 1 The Reaction Process p. 560-567
HI CollisionsChapter 17 Section 1 The Reaction Process p

14 Chapter 17 Section 1 The Reaction Process p. 560-567
Activation EnergyChapter 17 Section 1 The Reaction Process p

15 Chapter 17 Section 1 The Reaction Process p. 560-567
Activation EnergyThe bonds of these reactants must be broken in order for new bonds to be formed.Bond BREAKING is an ENDOTHERMIC process, and bond FORMING is EXOTHERMIC.Activation energy, Ea, is the minimum energy required to transform the reactants into an activated complex.Chapter 17 Section 1 The Reaction Process p

16 Chapter 17 Section 1 The Reaction Process p. 560-567
Activated ComplexAn activated complex is a transitional structure that results from an effective collision and that persists while old bonds are breaking and new bonds are forming .An activated complex occurs at a high energy position along the reaction pathway.An activated complex is not the same as an intermediate. – An activated complex is short-livedChapter 17 Section 1 The Reaction Process p

17 Chapter 17 Section 1 The Reaction Process p. 560-567
Ch 17 Sec 1 HomeworkPage 567 # 1-8Chapter 17 Section 1 The Reaction Process p

18 Chapter 17 Section 1 The Reaction Process p. 560-567
Energy ProfileEChapter 17 Section 1 The Reaction Process pp. 564

19 Chapter 17 Section 1 The Reaction Process p. 560-567
Energy ProfilesEa = energy of activated complex − energy of reactants [reactants to A.C. on graph]Ea′ = energy of activated complex − energy of products [products to A.C. on graph]ΔEforward = energy of products − energy of reactants [reactants to products on graph]ΔEreverse = energy of reactants − energy of products [products to reactants on graph] |Eforward | = |Ereverse | same value; opposite signChapter 17 Section 1 The Reaction Process p

20 Endothermic Energy Profile
Chapter 17 Section 1 The Reaction Process p

21 Exothermic Energy Profile
Chapter 17 Section 1 The Reaction Process p

22 Energy Profile for HI Synthesis
notesEnergy Profile for HI SynthesisChapter 17 Section 1 The Reaction Process pp. 565

23 Chapter 17 Section 1 The Reaction Process p. 560-567
Sample Problems p. 566Copy the energy diagram below, and label the reactants, products, E, Ea, and Ea′. Determine the value of Eforward , Ereverse , Ea, and Ea′.Chapter 17 Section 1 The Reaction Process p

24 Chapter 17 Section 1 The Reaction Process p. 560-567
Sample Problems p. 566ΔEforward = energy of products − energy of reactantsΔEforward = 50 kJ/mol − 0 kJ/mol = +50 kJ/molΔEreverse = energy of reactants − energy of productsΔEreverse = 0 kJ/mol − 50 kJ/mol = − 50 kJ/molChapter 17 Section 1 The Reaction Process p

25 Chapter 17 Section 1 The Reaction Process p. 560-567
Sample Problems p. 566Ea = energy of activated complex − energy of reactantsEa = 80 kJ/mol − 0 kJ/mol = 80 kJ/molEa′ = energy of activated complex − energy of productsEa′ = 80 kJ/mol − 50 kJ/mol = 30 kJ/molChapter 17 Section 1 The Reaction Process p

26 Chapter 17 Section 1 The Reaction Process p. 560-567
Practic Problems p. 5671. a. Use the method shown in the sample problem to redraw and label the following energy diagram. Determine the value of ΔEforward, ΔEreverse, Ea, and Ea′.b. Is the forward reaction shown in the diagram exothermic or endothermic? Explain your answer.Chapter 17 Section 1 The Reaction Process p

27 Chapter 17 Section 1 The Reaction Process p. 560-567
Practic Problems p. 5672. a. Draw and label an energy diagram similar to the one shown in the sample problem for a reaction in which Ea = 125 kJ/mol and Ea′ = 86 kJ/mol. Place the reactants at energy level zero.b. Calculate the values of ΔEforward and ΔEreverse.c. Is this reaction endothermic or exothermic? Explain your answer.Chapter 17 Section 1 The Reaction Process p

28 Chapter 17 Section 1 The Reaction Process p. 560-567
Practic Problems p. 5673. a. Draw and label an energy diagram for a reaction in which Ea = 154 kJ/mol and ΔE = 136 kJ/mol.b. Calculate the activation energy, Ea′, for the reverse reaction.Chapter 17 Section 1 The Reaction Process p

29 Chapter 17 Section 1 The Reaction Process p. 560-567
Ch 17 Sec 1 HomeworkEnergy Diagram WorksheetChapter 17 Section 1 The Reaction Process p

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