CHEM 121
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Today’s outline
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Introductions
Learning styles
Scientific Method
Chemistry
Matter and measurement
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Background in civil and
environmental
engineering
◦ Researched the removal
of metals from the
subsurface by using
polymers excreted by
bacteria
◦ Interested in how science
and technology impact
society and vise versa
Call me Anna
About me
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Let’s get to know each other
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Any nicknames?
Why are you taking this course?
What’s your educational/career goal?
How long have you been at North?
Anything you’d like to share?
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Understanding your learning style allows you
to come up with a more successful study plan
Some people use one sense more than others
while learning
◦ Visual
◦ Auditory
◦ Tactile
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Focus on what works for you
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Relate most effectively to written information,
notes, diagrams, and pictures
Study tips
◦ Take notes even when you have handouts
◦ Look at (don’t just listen) to study materials and
directions
◦ Make your own charts/maps/notes/flashcards
◦ Try visualizing words and concepts in your head
◦ Write everything down
◦ Make review sheets that you can refer back to
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Read your assignments and study materials
out loud
Record lectures or listen to videos to help you
fill in gaps in your notes
◦ Lots of podcasts and videos available online and
through publisher that you can listen to
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Sit up towards the front of a classroom so
that you can hear clearly
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Try typing your notes
Use real objects when possible or just act out
what you are reading/learning about
◦ Make models
◦ Do practice problems
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Role-playing helps
Plan out and give explanations/
demonstrations on class topics
◦ See me if you’d like to make a presentation on a topic
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Use the lab portion of the class to help solidify
ideas
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Must be testable
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Hypothesis must be testable and falsifiable
Experiments and observations must be repeatable
Limited by technology of the day
Data either supports or falsifies your hypothesis
Cannot make value judgments
◦ Cannot determine if something is “bad” or “good”
◦ Humans can use results to advance their causes, but
the method itself only generates unbiased data
◦ Discoveries are neither bad nor good – humans and
societies decide how to use new information/ideas
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Very Brief History
◦ 430 BC Democritus proclaims the atom to be the simplest unit of
matter/all matter made of atoms
◦ 300 BC Aristotle declares existence of only four elements: fire, air,
water and earth
 All matter is made up of these four elements
 Matter had four properties: hot, cold, dry and wet
◦ 300 BC alchemists start trying to turn cheap metals into gold
 In 1520 they start also looking for the elixir of life
 In 17th century Robert Boyle puts an end to alchemy with The Skeptical
Chemist
◦ End of 17th Century -Mid 19th Century
 Traditional chemistry
◦ Mid 19th Century - Present
 Modern chemistry
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Chemistry is the study of matter – its
composition, properties, and transformations
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Matter is anything that has mass and takes up
volume (occupies space)
◦ Mass is a measurement of the amount of matter in
an object
◦ Can be natural or synthetic (human-made)
◦ Note: Mass and weight are not the same thing
 Weight is a measurement of how hard gravity is pulling
on an object
 Mass will remain the same wherever an object is
 Weight will change depending on the force of gravity
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Solid
◦ Has a definite volume
◦ Maintains its shape regardless of its container
◦ Particles lie close together in a regular pattern
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Liquid
◦ Has a definite volume
◦ Takes the shape of its container
◦ Particles are close together but can move past one
another
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Gas
◦ Has no definite volume – will fill any available space
◦ Takes the shape of its container – fills container
◦ Particles are very far apart and move around randomly
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Properties that can be observed or measured
without changing the composition of the
material
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Boiling point
Melting point
Solubility
Color
Odor
State of matter
Density
And many others
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Properties that determine how a substance
can be converted to another substance
◦ Chemical change is the chemical reaction that
converts one substance into another
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Pure Substance
◦ Composed of only a single component (atom or
molecule)
◦ Constant composition regardless of size or origin
◦ Cannot be broken down into other pure substances by a
physical change
◦ Fixed physical and chemical properties
◦ Examples:
 Elements – each element is a pure substance that cannot be
broken down by a chemical change
 Compounds- pure substances formed by chemically joining
two or more elements
 Water (H20)
 Table salt (NaCl)
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Mixture
◦ Composed of more than one component.
◦ The composition can vary depending on the sample
◦ Can have varying composition (any combination of
solid, liquid, and gas)
◦ Can be separated into their components by a
physical process
◦ Can be homogenous (maple syrup) or
heterogeneous (vinagrette)
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Why do we take measurements?
What kinds of measurements do you take
throughout the day?
Why do we use standard measurements?
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Two main systems of measurement
◦ English system
 Used in the US and a handful of small countries as
system of measurement
◦ Metric system
 Used by most of the world as the system of
measurement
 Used for scientific research
 Used in the medical field
 Will be the units used throughout this course
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The prefix of the unit name indicates if the
unit is larger or smaller than the base unit by
factors of 10
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Example: Length
Base unit = meter (m)
1 kilometer (km) = 1,000 meters (m)
1 km = 1,000 m
I millimeter (mm) = 0.001 meters (m)
1mm = 0.001 m
1centimeter (cm) = 0.01 meter (m)
1 cm = 0.01 m
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Example: mass
Base unit = gram (g)
1 kilogram (kg) = 1,000 grams (g)
1 kg = 1,000 g
I milligram (mg) = 0.001 g (g)
1mg = 0.001 g
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Example: volume
Base unit = liter (L)
1 kiloliter (kL) = 1,000 meters (L)
1 kL = 1,000 L
I milliliter (mL) = 0.001 meters (L)
1mL = 0.001 L
Volume = length x width x height
= cm x cm x cm
= cm3
1 mL= I cm3 = 1cc
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Exact numbers
◦ Results from counting objects or is part of a
definition
 10 fingers
 23 students in a class
 1 meter = 100 centimeters
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Inexact numbers
◦ Results from a measurement or observation and
contains some uncertainty
 10 cm
 23 g
 754.5 mL
http://www.thetangoboutique.com/wp-content/uploads/2013/05/paulina_heel_measure.jpg
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All of the digits in a measured number
including one estimated digit
All nonzero digits are always significant
Examples
◦ 39.5 m has 3 significant figures
◦ 9562.5874 m has 8 significant figures
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Rule 1: A zero counts as a significant figure
when it occurs:
◦ Between two nonzero digits
 36.054 mL has 5 significant figures
 3.004 cm has 4 significant figures
◦ At the end of a number with a decimal place
 7.2500 s has 5 significant figures
 360. km has 3 significant figures
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Rule 2: A zero does not count as a significant
figure when it occurs
◦ At the beginning of a number
 0.00546 mg has 3 significant figures
 0.03 cc has 1 significant figure
◦ At the end of number that does not have a decimal
place
 3560 s has 3 significant figures
 2356000 km has 4 significant figures
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Multiplication and Division
◦ The answer has the same number of significant
figures as the original with the fewest figures (you
are limited by the least precise number)
4 sig. figures
351.2 miles
= 63.854545 miles
5.5 hour
hour
2 sig. figures
Answer must have
2 sig. figures.
to be retained to be dropped
63.854545 miles = 64 miles
hour
hour
first digit to be dropped
If the first digit
to be dropped is:
2 sig. figures
Answer
Then:
•between 0 and 4
•drop it and all remaining digits
•between 5 and 9
•round up the last digit
to be retained by adding 1
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Addition and Subtraction
◦ The answer has the same number of decimal places
as the original number with he fewest decimal
places
10.11 kg 2 decimal places
3.6 kg
1 decimal place
6.51 kg answer must have
1 decimal place
=
6.5 kg
final answer
1 decimal place
y x 10x
Coefficient:
A number between
1 and 10.
Exponent:
Any positive
or negative
whole number.
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If the decimal place is moved to the left x is
positive
◦ 280 = 2.8 X 102
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If the decimal place is moved to the right x is
negative
◦ 0.028 = 2.8 X 10-2
• Conversion factor: A term that converts a quantity in
one unit to a quantity in another unit.
original
quantity
x
conversion factor
desired
= quantity
• Conversion factors are usually written as
equalities.
2.21 lb = 1 kg
• To use them, they must be written as fractions.
2.21 lb
1 kg
or
1 kg
2.21 lb
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Factor-label method: Using conversion factors to
convert a quantity in one unit to a quantity in
another unit.
•units are treated like numbers
•make sure all unwanted units cancel
To convert 130 lb into kilograms:
130 lb x
original
quantity
conversion factor
= ? kg
desired
quantity
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Can be inverted as needed to have units
cancel out
2.21 lb
1 kg
130 lb
x
or
1 kg
2.21 lb
Answer
2 sig. figures
= 59 kg
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Sometimes you’ll have to use multiple
conversion factors
◦ Always arrange the factors so that the denominator
(bottom) cancels the numerator (top) in the
preceding term
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A measurement of how hot or cold an object
is
Three common temperature scales
◦ Degrees Fahrenheit (oF)
◦ Degrees Celcius (oC)
◦ Kelvin (K)
To convert from oC to oF:
oF
= 1.8(oC) + 32
To convert from oC to K:
K =
oC
+ 273
To convert from oF to oC:
oC = oF − 32
1.8
To convert from K to oC:
oC
= K − 273
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A physical property that relates the mass of a
substance to its volume
density
=
To convert volume (mL)
to mass (g):
g
mL x
= g
mL
density
mass (g)
volume (mL or cc)
To convert mass (g)
to volume (mL):
mL
g x
= mL
g
inverse of density
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A quantity that compares the density of a
substance with the density of water at the
same temperature
specific gravity
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=
density of a substance (g/mL)
density of water (g/mL)
The units cancel out so it is dimensionless
If SG > 1 the fluid is more dense than water
If SG < 1 the fluid is less dense than water