Chemistry 13
Dr. Tom Mallouk
Section 001
MWF 8:00-8:50 am
Phone 863-9637
Email: tom@chem.psu.edu
Office hours: M 10-11, T 9-10 (or by appointment)
224 Chemistry
TA: Laurie Heinicke, lah329@psu.edu
TEXTS
Brown, LeMay, & Bursten, Chemistry: The Central Science,
9th Ed., 2003 (required)
Supplementary Reading on course website,
http://courses.chem.psu.edu/chem13 (required)
Wilson Solutions to Exercises, The Central Science, 9th ed.
(recommended)
Chem 12 - Chemical principles
• Covered the basics (Ch. 1-4, 10)
• Thermochemistry, periodicity, bonding
• How structure affects properties and function
Chem 13 - Quantitative understanding of reactions
• Will a reaction occur? (thermodynamics)
• How fast will it go? (kinetics, nuclear chemistry)
• Quantitative equilibria:
Acid-Base, Solubility, Oxidation-Reduction
• Inorganic materials, their properties, and applications
“I often say that when you can measure what you are
speaking about, and express it in numbers, you know
something about it; but when you cannot measure it, when
you cannot express it in numbers, your knowledge is of a
meagre and unsatisfactory kind.” - Lord Kelvin, 1883
Lectures in Chem 13
•
•
•
•
3x per week, no recitation
There is no such thing as a stupid question!
In-class problem solving and Friday quizzes
Demonstrations are part of the fun (and also on the
exam!)
Homework
• Is not collected, but is important preparation for on-line
quizzes and midterm exams
• Office hours and tutoring sessions are a good time to
discuss homework problems
Your grade in Chem 13
• Exams - 70%
3 midterms + comprehensive final
• Quizzes - 30%
In class and web-based quizzes
Grading scale:
A :91, A-:88, B+:85, B:80, B-:77, C+:74, C:65,
D:54
See course website for full description:
http://courses.chem.psu.edu/chem13
• Interactive Schedule contains links to homework, quizzes,
reading, exam locations, lecture notes
• Lecture notes on website - please print and bring to class
Also,
• TA contact information
• Detailed instructions for on-line quizzes
• e-Suggestion box
Four keys to success in Chem 13
• Manage your time
I expect 9-10 hrs per week consistently
(lecture, reading, homework, quizzes)
• Come to class
Sounds obvious (?!)
In-class quizzes are part of your grade
• Seek help
Do not wait to get help!
If you fall behind in this class, you will be in serious trouble!
Get help from me, the TA, and the tutors in the Chemistry
Resource Room (211 Whitmore)
• Choose your friends wisely
Cooperative study groups - OK to do homework together
You must do quizzes on your own.
CHEMICAL KINETICS - Ch. 14
Kinetics is the study of reaction rates.
Thermodynamics tells us if a reaction can occur but not
how fast. (More later)
Spontaneous reactions:
H2(g) + 1/2O2(g)  H2O(g)
(very exothermic, but very slow)
2NO2(g)  N2O4(g)
(weakly exothermic, but very fast)
Why are reaction rates important?
How quickly will food spoil? What can be done to slow or prevent it?
How do life processes (metabolism, respiration, photosynthesis)
work? What do enzymes do?
AVERAGE VS. INSTANTANEOUS RATES
Rate: change that occurs in a given interval of time.
Average speed: x / t = rate of travel
(change in position over change in time)
rate of school bus = distance traveled = x
time
t
x = xfinal – xinitial = 4 miles
t = tfinal – tinitial = 2:10 pm - 2:00 pm = 10 min
Speed =
But the instantaneous rate is always changing:
0 mph at red light, 60 mpg on highway
x dx

instantaneous rate = lim
t 0 t
dt
Chemical rate Laws describe instantaneous rates in terms of
 concentration
 time
Sample Question
[X]0
[X]
Slope of the line is
X 
t
[X]
time
t
The slope of the blue line indicated ([X]/t) represents
1. an instantaneous rate
2. an average rate
3. both
4. neither
REACTION RATES
We can express the rate of reaction in terms of:
1. appearance of products
2. disappearance of reactants
Stoichiometry of reaction tells us how these are related.
General case:
aA + bB  cC + dD
reactants
products
(a, b, c, d are stoichiometric coefficients)
 1 A  1 B   1 C   1 D 
rate 



a t
b t
c t
d t
Example
2HI(g)  H2(g) + I2(g)
6 moles of HI in a 1 L flask are converted to I2 and H2 in
1 min.
What is the rate of disappearance of HI?
What is the rate of appearance of I2? H2?
1.
2.
Twice the rate of disappearance of HI
1/2 the rate of disappearance of HI
FACTORS THAT AFFECT THE RATE
OF REACTIONS
1. The reactants
Chemical identity + physical state
(solid, liq, gas, solute, fine particles,…)
2. Concentration of reactants
Increasing conc.  faster rates (usually)
3. Temperature
Increasing T  faster rates
(almost always)
4. Presence of a catalyst
EFFECT OF CONCENTRATION
Rate Law: relationship between the reaction rate and
concentration of the reactants
aA + bB  cC + dD
reactants products
The rate law is:
rate (= d[A] /dt) = k[A]x[B]y
k is the rate constant
independent of [A] and [B]; varies with T
x and y are exponents
≥ 0, not necessarily integers
EFFECT OF CONCENTRATION
rate = k[A]x[B]y
Are x, y the same as a, b?
Sometimes yes, in general, no
(depends on reaction mechanism)
NOTE: dependence of rate on concentration MUST
be determined experimentally
It CANNOT be predicted from overall reaction
experiment  rate law  mechanism
(exponents x, y)
Examples of Rate Laws:
Rate = k[A]
= k[B]
= k[A]2
= k[A][B]