Chemistry 102(001) Fall 2012
CTH 328 10:00-11:15 am
Instructor: Dr. Upali Siriwardane
e-mail: upali@latech.edu
Office: CTH 311 Phone 257-4941
Office Hours: M,W 8:00-9:00 & 11:00-12:00 am;
Tu, Th, F 8:00 - 10:00am..
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
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:
Syllabus and Grading
1) Three tests
2) 11 Group-Homeworks (GHW)
3) 20 Quizzes and attendance
4) 3 OWL assignments
Bonus
1) Bonus Assignment
2) Bonus Point-class participation
600 (60%)
200 (20%)
100 (10%)
100 (10%)
1000 (100%)
40 (4%)
10 (1%)
Complete the syllabus questionnaire
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GHW# 1: Chapter 13
Chemical Kinetics: Reaction Rates
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Chapter 13. Chemical Kinetics
13.1
13.2
13.3
13.4
13.5
Reaction Rate
Effect of Concentration on Reaction Rate
Rate Law and Order of Reaction
A Nanoscale View: Elementary Reactions
Temperature and Reaction Rate: The Arrhenius
Equation
13.6 Rate Laws for Elementary Reactions
13.7 Reaction Mechanisms
13.8 Catalysts and Reaction Rate
13.9 Enzymes: Biological Catalysts
13-10Catalysis in Industry
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Why Study Rates of Reactions?
1) Rates show us how fast/slow a reaction would
2)
3)
4)
5)
take place.
We need make some reactions go faster.
Some reactions needed to be slowed down.
We need the conceptual back ground
understand 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)
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Reaction of cis-platin with Water
Substitution reaction
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Disappearance of Color
Intensity of Color is proportional to amount of
reactant
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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
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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
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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.
rate = (D[NO2]/ D t = - 4/2 D[N2O5]/ D t
D[O2]/ D t = - 1/2 D[N2O5]/ D t
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1) What is the rate of a chemical reaction? (Describe
in your own words and then in equation)
a A ----> b B + c C
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2) Answer the following Given the chemical reaction:
2 N2O5 ----> 4 NO2 + O2
a) What’s the rate of disappearance ( or decomposition)
N2O5? (Equation)
b) What are the rates of appearance of NO2 and O2?
(Equations)
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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)
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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)
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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)
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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?
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Graphing Kinetics Data
2 N2O5(g) -----> 4 NO2 (g) + O2 (g)
Average rate =
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Graph of 2 N2O5(g) ---> 4 NO2 (g) + O2 (g)
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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?
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Graph
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Graph in Problem 7
Time / min
[N2O5] / moldm-
0
20
40
60
80
100
160
0.01756
0.00933
0.00531
0.00295
0.00167
0.00094
0.00014
3
0.02
0.015
0.01
Series1
0.005
0
0
50
100
150
200
5) At what time the reaction is complete?
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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?
-4
-3
-1
0-20 = 2.06 x 10 mol dm min
20-40 =
40-60
=
60-80
=
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7) How does reaction rate vary with time in the
graph? Consider the decomposition of N2O5.
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8)What are the main factors that affect a rate of a
chemical reaction?
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Factors that affect rates of
chemical reactions
a) Temperature
b) Concentration
c) Catalysts
d) Particle size of solid reactants
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Effect of Particle Size on Rate
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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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