Welcome to Chem103
Required Items
y Textbook: Chemistry: The Molecular Nature of Matter
and Change, Martin S. Silberberg, 5th Edition, McGraw-Hill,
2009
y iClicker
y Scientific calculator
y ACTIVE PARTICIPATION in class and lab
Use of iClicker
In each lecture, a handful of questions will be asked and you would need to
respond to with the clickers.
y Your responses to questions will be recorded. The purpose behind the clickers is
primarily to encourage you to think and respond to questions.You will be
awarded 80% for participation and an additional 20% for answering the
qquestions correctly.
y
y Your participation will also be used to monitor your attendance in lecture.
y The clicker responses will be used to award up to 3 extra-credit points to your
final semester grade. Therefore, please bring your clickers to every class. The
clickers are available for purchase at the University Bookstore. The University
has adopted iClicker as the campus standard. So you will need to purchase a
single iClicker for all of your classes.
1
Course Policies
¾ Lecture attendance will be monitored according to the University
policy.
¾ NO MAKE-UPS for labs, quizzes, or exams.
¾ Homework assignments mentioned in the course syllabus will not be
collected and graded.
graded However,
However the homework assignments that will
be handed over during class will be collected and graded.
¾ Must complete all lab work to pass the course.
Suggestions
y Read the assigned section(s) of the text thoughtfully before they are discussed in the
lecture.
y
Listen carefully to the lecture and take notes of important topics. Taking good notes
during a class is an important part of study preparation.
y
Discuss with your classmates about topics that you are having difficulties to
understand. I believe students can learn a lot through discussions with their classmates.
understand
classmates
y
Work all the recommended end-of-chapter exercises. Think about the problem and your
answer. Check your answers against those at the back of the book but DO NOT look at those
before trying the problem.
y
FINALLY, please do not wait TOO LONG to get help. Don’t hesitate to seek help from me if
you are having any problem in understanding the lecture material. Feel free to drop me an email or
simply stop by my office if you have any questions. One-to-one conversation is sometime helpful to
understand the difficult topics.
Goals and Expectations
¾ Goals
¾ Develop an atomic/molecular level picture of matter
¾ Use the atomic/molecular level picture to explain chemical and physical
properties of matter
¾ Develop practical lab skills
¾ Expectations
p
comingg in
¾ Understand Chapter 1
¾ Know the metric units and prefixes (Tables 1.3 and 1.4)
¾ Comfortable with scientific notation
¾ Competent with basic algebraic manipulations
¾ Know how to use your calculator
¾ Know the names and symbols for elements 1-88
2
Chapter 1
Keywords
y Matter
y Physical and Chemical properties
y Physical and Chemical changes
y Qualitative and quantitative observations
y Units of measurements
y Precision, Accuracy, and Experimental Error
y Scientific notation and Significant figures
Matter at the Macroscopic and Particulate Levels
Chemistry & Matter
We can explore the MACROSCOPIC world —what we can see
—
to understand the PARTICULATE (microscopic) worlds we
cannot see.
We write SYMBOLS to describe these worlds.
We build up MODELS of their interactions
Predict MACROSCOPIC properties
3
Matter and its Reactivity
2Na(s) + Cl2(g) → 2NaCl(s)
Chemistry is the study of the properties and transformations
of matter.
Physical Properties
What are some physical properties?
y color
l
y melting and boiling point
y Odor
y Density
Physical Changes
Some physical changes would be
¾ boiling of a liquid
¾ melting of a solid
¾ dissolving a solid in a liquid to give a
g
mixture — a
homogeneous
SOLUTION.
4
Chemical Properties and Chemical Changes
¾ Chemical change or chemical reaction — transformation of one or more
atoms or molecules into one or more different molecules.
Physical or Chemical Changes?
1. A molecule disintegrates upon heating?
A. Chemical change
B. Physical Change
2. Two molecules react and form new molecule
A. Chemical change
B. Physical Change
Physical or Chemical Changes?
1. Molecules form new interactions upon cooling
A. Chemical change
B. Physical Change
2. Molecules breaks up these interactions upon heating
A. Chemical change
B. Physical Change
5
Physical or Chemical Changes?
Physical or Chemical Changes?
1. Formation of snow
A. Chemical change
B. Physical Change
2. Breakingg of gglass
A. Chemical change
B. Physical Change
3. Corroding metal
A. Chemical change
B. Physical Change
Physical or Chemical Changes?
4. A rusting bicycle
A. Chemical change
B. Physical Change
5. Melting butter for popcorn
A. Chemical
h
l change
h
B. Physical Change
6. Bleaching your hair
A. Chemical change
B. Physical Change
6
Physical or Chemical Changes?
7. Fireworks exploding
A. Chemical change
B. Physical Change
8. Squeezing oranges to make orange juice
A. Chemical
h
l change
h
B. Physical Change
9. Boiling egg
A. Chemical change
B. Physical Change
Intensive and Extensive Properties
¾ INTENSIVE property of matter does NOT depend on quantity
of matter.
Example: Density is an intensive property of matter
matter.
Temperature
¾EXTENSIVE property of matter depends on quantity of matter.
Example: mass and volume.
Types of Observations and Measurements
y We make QUALITATIVE observations of reactions — changes in
color and physical state.
y We also make QUANTITATIVE MEASUREMENTS, which involve
numbers. For example,
numbers
example if 10
10.00 g of iron reacts with 88.00 g of oxygen
oxygen,
how much iron oxide will form?
7
All of the following are examples
of intensive properties EXCEPT
a.
melting point.
b.
color.
c.
volume.
d.
density.
e.
boiling point.
Some problems
Which of the following observations are examples of chemical
changes to aluminum?
a.
b.
c.
d.
When aluminum reacts with hydrochloric acid, hydrogen
gas is evolved.
Aluminum melts at 660 °C.
A cube of aluminum with a volume of 4.0 cm3 has a
mass of 10.8 g.
Aluminum is a good electrical conductor.
Which one of the following is an example of physical change?
a. the evaporation of water
b. the rusting of iron
c. the combustion of hydrogen
d. the tarnishing of silver
e. both the rusting of iron and the tarnishing of silver
The Importance of Energy in the Study of Matter
¾ Energy is the ability to do work
y Potential energy: energy due to the position of the object
y Kinetic energy: energy due to the motion of the object
¾ Energy
E
is
i neither
ith created
t d nor ddestroyed-it
t
d it is
i always
l
conserved as it is converted from one form to the other
¾ In nature, situations with lower energy is favored over those
of higher energy
Potential Energy is Converted to Kinetic Energy
8
Potential Energy is Converted to Kinetic Energy
The Scientific Approach: Developing a Model
Units of Measurement
y Use SI units — based on the metric system
9
Units of Length
y 1 kilometer (km) = ? meters (m)
y 1 meter (m) = ? centimeters (cm)
y 1 centimeter (cm) = ? millimeter (mm)
y 1 nanometer (nm) = 1.0 x 10-9 meter
O—H distance =
9.58 x 10-11 m
9.58 x 10-9 cm
0.0958 nm
Units of Length
1.
a.
b.
c.
d.
Express 100 Km in cm
107
106
104
102
2.
a.
b.
c.
d.
1 Å = 10–10 m=10–1 nm
3. Express 10 nm in Å
a. 102
b. 10–2
c. 104
d. 10–4
Express 10 nm in cm
10–2
10–4
10–3
10–6
1 pm =10–12 m = 10–3nm
4.
a.
b.
c.
d.
Express 10 nm in pm
10–2
104
10–3
106
Temperature Scales
Boiling point
of water
Freezing point
of water
Fahrenheit
Celsius
Kelvin
212 ˚F
100 ˚C
373 K
180˚F
180
F
100˚C
100
C
32 ˚F
0 ˚C
100 K
273 K
Notice that 1 kelvin degree = 1 degree Celsius
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Temperature Scales
Kelvin
Celsius
Fahrenheit
F - 32 C
=
9
5
32 F =A. 100 C
B. 9 C
C. 0 C
D. -17.7 C
C = K − 273
0 K = A. -273 C
B. 305 C
C. 0 C
D. -305 C
Calculations Using Temperature
•Generally require temp’s in kelvins
T (K) = T (˚C) + 273.15
•Body temp = 37 ˚C + 273.15 = 310.15 K
•Liquid nitrogen = -196 ˚C + 273.15 = 77.15 K
Playing with Numbers
1. What is 5-2 equal to?
A.
10
B.
-1/25
C.
1/25
D.
-25
E
E.
-1/64
1/64
F.
none of the above
3. Write the following number so it
has three significant figures: 340
A. 340
B. 3.40 x 102
C. 340 x 10-2
D. 3.4 x 102
2. Round the following number to three
decimal places: 12.333333333
A. 12.3
B. 12.33
C. 12.333
D. 12.334
E. 12.330
4. 8.66 x 104 x 4.1 x 102 = ?
A.
3.6 x 107
B.
3.5 x 107
C.
3.55 x 107
D.
3.5506 x 106
E.
3.550 x 106
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Playing with Numbers
5. 3.56x102 + 1.92x103 = ?
(in proper scientific
notation)
A.
5.48x102
B.
2.28x103
7. Compute the following: 3.22+6.2*5.101
(pay attention to significant figures
after each step)
C.
2.276x103
A.
35.2
D
D.
22 76x102
22.76x10
B
B.
34 8
34.8
6. Round the following number to
four significant figures:
38219.99147
C.
35
D.
48
A.
E.
48.1
38219.9915
B.
38219.9914
C.
3822
D.
38210
E.
38220
Dimensional Analysis
¾ If the temperature of a hot water bath is 40.5 °C, what is the temperature in
Kelvin? In Fahrenheit?
Remember,
T (K) = T (˚C) + 273.15
Answer: 313.7 K and 105. °F
Dimensional Analysis
PROBLEM: Mercury (Hg) has a density of 13.6
g/cm3. What is the mass of 95 mL of Hg in grams?
In pounds?
First, note that 1
cm3 = 1 mL
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PROBLEM: Mercury (Hg) has a density of 13.6
g/cm3. What is the mass of 95 mL of Hg in grams?
In pounds?
Strategy
1. Use density to calc. mass (g) from volume.
Density =
mass (g)
volume (cm 3 )
Volume x density = mass
( 95 cm3 )(13.6 g/cm3) = 1.3 x 103 g
PROBLEM: Mercury (Hg) has a density of 13.6
g/cm3. What is the mass of 95 mL of Hg in grams?
In pounds?
2.
Convert mass (g) to mass (lb)
Need to know conversion factor
= 454 g / 1 lb
1.3 x 10 3 g •
Number in original unit x
1 lb
= 2.8 lb
454 g
new unit
original unit
= New number in new unit
Dimensional Analysis
y A can of Coca-Cola contains 12 quarts (qt). What is the volume in
fluid ounces (fl oz)? (1qt ≡ 32 fl oz)
N b in
Number
i original
i i l unit
i x
12 fl oz
x
new unit
original unit
1 qt
32 fl oz
= New
N number
b in
i new unit
i
= 0.38 qt
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Dimensional Analysis
¾ A marathon race covers a distance of 42.195 km. What is this distance in
meters?
A.
B.
C.
D.
4.2195 x 104 m
4.22 x 104 m
4.2195 x 10-4 m
4.219 x 104 m
A.
B.
C.
D.
26.219 miles
67.903 miles
26.22 miles
67.90 miles
¾ In miles? ( 1 km ≡ 0.62140 miles)
Dimensional Analysis
¾ A marathon race covers a distance of 42.2 km. What is this distance in
meters?
A.
B.
C.
D.
4.2195 x 104 m
4.22 x 104 m
4.2195 x 10-4 m
4.219 x 104 m
A.
B.
C.
D.
26.219 miles
67.903 miles
26.22 miles
67.90 miles
¾ In miles? ( 1 km ≡ 0.6214 miles)
Dimensional Analysis
¾ How many Å3 are there in 50. m3? (1 Å =10-10 m)
A.
B.
C.
D
D.
5.0 x 1031 Å3
5.0 x 10-31 Å3
5 x 1011 Å3
11 Å3
5 x 10-11
¾ Convert the 50.m3 volume in L? ( 1 m = 102 cm; 1000 cm3 = 1L)
A.
B.
C.
D.
5.0 L
5.0 x 102 L
5.0 x 103 L
50. x 103 L
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Exponential or Scientific notation
Exponential or Scientific notation: Presenting a very large or
small numbers in a compact and consistent form for simplification in
calculations.
Example: Speed of light = 299800000 m s-1
(a very big number!)
A red blood cell has a diameter of 0.0000075 m
(a very small number!)
Speed of light = 2.998 x 108 ms-1 (in a compact form!)
A red blood cell diameter = 7.5 x 10-6 m
Scientific notation: expressed as a product of two numbers: N x 10n, where
N is the digit term and 10n, the exponential term.
Significant Figures
Significant figures are digits in a measured quantity (expressed in a scientific
notation) that reflect the accuracy of the measurement.
Scientific notation
Sig.
g Figs.
g
0.0156
0.1560
15600
¾Zeros at the left of a nonzero number are not significant
¾Zeros at the right of a nonzero number (trailing zero) are significant
provided there is decimal point before the nonzero number.
Significant Figures
a. 1.567 cm + 2.4791 cm + 1.25 cm
1.567 (4 sig figs, three digits after the decimal)
2.4971 (5 sig figs, four digits after the decimal), most precise
1.25 (3 sig figs, 2 digits after the decimal point), least precise
Sum: 5.3141, corrected to 5.31 cm
b. 315.15 mL + 28 mL = 343. mL
c. 0.120 cm x 0.08206 cm = 0.202 cm2
d. 241.0/23.5 = 10.3
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Dimensional Analysis
¾ 1 mole of a substance is typically expressed by the MW of any
chemical in grams? Atomic weight of sodium is 22.9898 and that of
chlorine is 35.4527. What is the MW of NaCl?
A. 58.4425
B. 58.443
C 58.4
C.
58 4
¾ You were asked to weigh 5.03 moles of NaCl. What is the amount
in grams?
A. 294
B. 293.9 L
C. 293.977 L
Dimensional Analysis
¾ 5.03 moles of NaCl is dissolved in 1L of water. What is the
concentration in g/L?
A.
B.
C.
D
D.
294
5.03
58.4
No idea
A.
B.
C.
D.
294
5.03
58.4
Not sure
¾ In mol/L
Dimensional Analysis
¾ A piece of metal has a density of 2.65 g/cm3 and a
mass of 2.50 g. What is the volume of the piece of
metal in liter? (1 liter = 1000 cm3)
A. 0.94 x 10-3 L
B. 9.4 x 10+3 L
C. 9.4 x 10-3 L
D. 0.94 x 10+3 L
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Precision, Accuracy, and Experimental Error
Precision: how close the measurements in a series are to each other
Accuracy: how close a measurement is to the actual value
Error: Deviation from actual value
Systematic Error and Random Error
Scientific notation and Significant figures
Average value of a variable x :
Group A reported: 5.43333 ± 0.00003
Group B reported: 5.23333 ± 0.00345
Group C reported: 5
5.33333
33333 ± 0.00001
0 00001
The real value was 5.2.
Whose measurement
was least precise?
A.
B.
C.
Whose measurement
was most accurate?
A.
B.
C.
Scientific notation and Significant figures
Average value of a variable x :
Group A reported: 5.43333 ± 0.00003
Group B reported: 5.23333 ± 0.00345
Group C reported: 5
5.33333
33333 ± 0.00001
0 00001
The real value was 5.2.
Whose measurement
was most precise?
A.
B.
C.
Whose measurement
was least accurate?
A.
B.
C.
17