Chemistry 18.5 Slide 1 of 21 18.5 The Progress of Chemical Reactions During the course of the Tour de France, cyclists travel almost 4000 kilometers with.

Transcript Chemistry 18.5 Slide 1 of 21 18.5 The Progress of Chemical Reactions During the course of the Tour de France, cyclists travel almost 4000 kilometers with.

Chemistry 18.5

Slide 1 of 21

18.5

The Progress of Chemical Reactions

During the course of the Tour de France, cyclists travel almost 4000 kilometers with steep mountains at 1600 meters or more. Crossing these high mountains requires extra energy. Chemical reactions can be thought of as processes involving peaks and valleys also. You will learn about the energy of a chemical reaction.

Slide 2 of 21

18.5

The Progress of Chemical Reactions > Rate Laws

Rate Laws

What is the general relationship between the value of the specific rate constant, k, and the speed of a chemical reaction?

Slide 3 of 21

18.5

The Progress of Chemical Reactions > Rate Laws

The

rate law

is an expression for the rate of a reaction in terms of the concentration of reactants. The

specific rate constant

(

) for a reaction is a proportionality constant relating the concentrations of reactants to the rate of the reaction.

Slide 4 of 21

18.5

The Progress of Chemical Reactions > Rate Laws The value of the specific rate constant, k, is large if the products form quickly; the value is small if the products form slowly.

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The Progress of Chemical Reactions > Rate Laws Animation 24

Observe the characteristics of a first-order reaction.

Slide 6 of 21

18.5

The Progress of Chemical Reactions > Rate Laws

In a

first-order reaction

, the reaction rate is directly proportional to the concentration of only one reactant. As the concentration of that reactant decreases, the rate of the reaction also decreases.

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18.5

The Progress of Chemical Reactions > Rate Laws

Slide 8 of 21

Conceptual Problem 18.2

Slide 9 of 21

Conceptual Problem 18.2

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Conceptual Problem 18.2

Slide 11 of 21

Practice Problems for Conceptual Problem 18.2

Problem Solving 18.36

Solve Problem 36 with the help of an interactive guided tutorial.

Slide 12 of 21

18.5

The Progress of Chemical Reactions > Reaction Mechanisms

Reaction Mechanisms

What do the hills and valleys in a reaction progress curve represent?

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18.5

The Progress of Chemical Reactions > Reaction Mechanisms

elementary reaction

is a reaction in which reactants are converted to products in a single step. The series of elementary reactions or steps that take place during the course of a complex reaction is called a

reaction mechanism.

intermediate

is a product of one of the steps in the reaction mechanism.

Slide 14 of 21

18.5

The Progress of Chemical Reactions > Reaction Mechanisms

A reaction progress curve shows an activation energy peak for each elementary reaction.

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18.5

The Progress of Chemical Reactions > Reaction Mechanisms The peaks correspond to the energies of the activated complexes. Each valley corresponds to the energy of an intermediate.

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18.5 Section Quiz.

Assess students’ understanding of the concepts in Section 18.5.

Continue to: Launch:

-or-

Section Quiz Slide 17 of 21

18.5 Section Quiz.

1. Choose the correct words for the spaces. If the specific rate constant,

, is _________, then products form __________.

a. large, slowly b. large, quickly c. small, quickly d. small, a first order reaction

Slide 18 of 21

18.5 Section Quiz.

2. Choose the correct words for the spaces. In a graph that shows the progress of a reaction, the peaks in the curve correspond to the energies of the _______ and the valleys correspond to the energies of the ________. a. activated complexes, reactants b. intermediates, activated complexes c. reactants, products d. activated complexes, intermediates © Copyright Pearson Prentice Hall

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18.5 Section Quiz.

3. Which of the following statements is true? a. Most reactions are elementary reactions.

b. In most reactions, reactants are converted to products in a single step.

c. Most reactions take place in a series of steps called intermediates.

d. Most reactions take place in a series of steps called a reaction mechanism.

Slide 20 of 21

18.5 Section Quiz.

4. The reaction mechanism can best be determined from a. the specific rate constant.

b. the overall chemical reaction.

c. the rate law.

d. experimentation.

Slide 21 of 21

Chemistry 18.5 Slide 1 of 21 18.5 The Progress of Chemical Reactions During the course of the Tour de France, cyclists travel almost 4000 kilometers with.

Transcript Chemistry 18.5 Slide 1 of 21 18.5 The Progress of Chemical Reactions During the course of the Tour de France, cyclists travel almost 4000 kilometers with.

The Progress of Chemical Reactions

Rate Laws

Reaction Mechanisms

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