1. © 2013 Pearson Education, Inc. Chapter 9, Section 1 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 9 © 2013 Pearson Education, Inc. Reaction Rates and Chemical Equilibrium 9.1 Rates of Reactions Lectures

2. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Collision Theory of Reactions A chemical reaction occurs when  collisions between reactant molecules have sufficient energy to break their bonds.  molecules collide with the proper orientation.  bonds between atoms of the reactants (N 2 and O 2 ) are broken and new bonds (NO) form. 2

3. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Collision Theory of Reactions A chemical reaction does not take place if the  collisions between reactant molecules do not have sufficient energy to break their bonds, or if  molecules are not properly aligned. 3

4. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Activation Energy Activation energy is the minimum energy needed for a reaction to take place or break the bonds between atoms of reactants. 4

5. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Reaction Rate The rate of reaction is determined by measuring the amount of reactant used up or product formed in a certain period of time. The rate or reaction is affected by  temperature changes.  changes in concentrations.  the presence of a catalyst. 5

6. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Reaction Rate and Temperature At higher temperatures,  the increase in kinetic energy causes the reacting molecules to move faster,  more collisions occur, and  more colliding molecules have sufficient energy to react and form products. For example, we refrigerate perishable foods to slow down the reactions that cause spoilage. 6

7. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Reaction Rate and Concentration Increasing the concentration of reactants  increases the number of collisions and  increases the reaction rate. 7

8. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Reaction Rate and Catalysts A catalyst  speeds up the rate of a reaction.  lowers the energy of activation.  is not used up during the reaction. Insert reaction rate and catalysis top pg 5 8

9. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Learning Check State the effect of each change on the rate of reaction as increases, decreases or no change. 1. increasing the temperature 2. removing some of the reactants 3. adding a catalyst 4. placing the reaction flask in ice 5. increasing the concentration of a reactant 9

10. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Solution State the effect of each on the rate of reaction as increases, decreases, or no change. Rate of Reaction 1. increasing the temperatureincreases 2. removing some of the reactantsdecreases 3. adding a catalystincreases 4. placing the reaction flask in icedecreases 5. increasing the concentration of a reactantincreases 10

11. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Learning Check Indicate the effect of each factor listed on the rate of the following reaction as increases, decreases, or does not change. A. raising the temperature B. removing some O 2 C. adding a catalyst D. lowering the temperature 11

12. © 2013 Pearson Education, Inc. Chapter 9, Section 1 Solution Indicate the effect of each factor listed on the rate of the following reaction as increases, decreases, or does not change. A. raising the temperatureincreases B. removing some O 2 decreases C. adding a catalystincreases D. lowering the temperaturedecreases 12