Contributed by:
The key highlights are:
1. What is chemistry?
2. How can the problems be solved in a systematic manner?
3. Precision and accuracy
4. Metric system
5. Uncertainty in Measurements
1.
AIM # 1: What is
Chemistry?
DO NOW: Answer the following questions
1.What is Chemistry?
-is the study of the composition of
substances and the changes they
undergo
- science of matter, an interaction
between atoms
2.
UNIT 1
INTRODUCTION AND
MEASUREMENT
•What is Chemistry?
•How can problems be solved in a systematic
•How do we give meaning and dimension to
our descriptions of the world around us?
•How can units be used to solve problems?
•How do we perform simple calculations
during experiments?
3.
AIM: What is Chemistry?
2. What are the four main divisions of chemistry?
1.Organic chemistry: the study of substances that contain carbon
Example: How gasoline is produces from oil
2. Inorganic chemistry: the study of substances without carbon
Example: how table salt reacts with different acids
3. Analytical chemistry: the study of the quantitative composition
of substances
Examples: how much chlorine is in a sample of tap water
4. Biochemistry: the study of chemistry of living organisms
Examples: how sugar in the blood stream of cats affect
insulin production
5.
AIM: What is Chemistry?
- everyday examples (you do not have to
write this down!!!!)
1. Digestion; enzymes promoting chemical reactions that power
our bodies. Lifting your arm requires your body to make and
burn ATP using oxygen with carbon dioxide as one of the
waste gases produced.
2. Cooking is the heating and combination of compounds to
make something new. In some cases, like rising bread we have
an actual chemical reaction where the yeast changes the food.
3. When concrete dries and hardens the water actually causes a
chemical reaction with the cement making a binding action
drying concrete isn't just losing water it is undergoing a
chemical change and one that creates heat as well (an
exothermic reaction).
6.
AIM: What is
Chemistry?
- everyday examples
4. When you write with ink on paper, the ink and paper unite in a
chemical reaction so that you can't erase it. Specialized inks allow
a short period where you can erase some inks, but most inks dry
and can't be erased; they have bound with the paper. This
includes your pen and your ink jet printer.
5. Plastics are all about organic chemistry.
6. The sun undergoes fusion and yes that too is chemistry. It
creates radiation and photons so we can see. Some of the
radiation interacts with oxygen to create ozone and the ozone
layer shields us from harmful UV radiation.
7.ANYTHING that burns is undergoing a chemical reaction and
almost always creates some form of carbon as waste.
7.
AIM# 2: How can problems
be solved in a systematic
manner?
• The scientific method is a way to solve a
scientific problem. It is an approach to a
solution (using mostly common sense)
8.
AIM: How can problems be solved
in a systematic manner?
- Steps of the Scientific Method
1. Objective (Problem): statement of purpose
2. Hypothesis (Prediction): Educated guess, in
the form: if …. then…
3. Experiment (Test): to test hypothesis, must
give reproducible results to be reliable
Variable: factor being tested
Control: other factors that are held constant
9.
AIM: How can problems be solved
in a systematic manner?
- Steps of the Scientific Method
4. Observations (Data): collect and gather data
based on your observations; organize these
results to perform analysis in the form of
charts, tables or graphs
a) Qualitative
b) Quantitative
5. Analysis: (Results): organizing data into
meaningful groups, tables, graphs, charts
10.
6. Conclusions: the determination if your
hypothesis was correct, it may be accepted,
rejected revised
7. Follow up/application: a repeat with
modification is sometimes necessary, and a
reevaluation of the results. Also answering
one question often leads to new questions.
How could you use and communicate the
information of your experiment. Why is it
important and who could benefit from it?
12.
AIM: How can problems be solved
in a systematic manner?
- Law vs. Theory
Theory: explains the results of experiments,
they can change or be rejected over time
because of results from new experiments
Law: describes natural phenomena, it tells
what happens and does not attempt to
explain why the phenomena occurs (that is
the purpose of a theory). Laws can often be
summarized by a math equation
13.
Precision and Accuracy
• Accuracy- closeness of a value to the true
value
• Hitting the bullseye when you are aiming for it
• For most experiments the accuracy means
how far the deviation is from the expected
value
• Precision- is the closeness of measurements
to each other
14.
(a) Accurate and precise- Casie
(b)Not precise, but one piece of data is accurate- Carmen
(c) Precise but not accurate- Cynthia
(d)Neither precise nor accurate - Cheryl
15.
AIM # 3: How can we give meaning
and dimension to our description of
the world around us? – Metric
• Measurement gives the universe meaning! How
tall are you? How much do you weigh? How old are
you? How fast can you run? How much volume do
you displace? All of these questions are designed
to give us reference to the world around us.
17.
AIM # 3 (a): How can we give
meaning and dimension to our
description of the world around us?
– Math Rules for Chem
19.
AIM: How can we give meaning
and dimension to our
description of the world around
us? – Sig Fig Rules
• Atlantic and Pacific
Rule:
• If a decimal point is present
(Pacific side) you start
counting from left to right
with the first non zero
number
• If a decimal point is absent
(Atlantic side) you start
count from right to left with
the first non zero number
20.
AIM: How can we give meaning
and dimension to our
description of the world around
us? – Sig Fig Rules
1.23.285 cm 5 ________________
1
2.8000 sec ________________
3.40. L 2
________________
4.2300 g 2
________________
21.
Calculating with sig figs
Multiplication and Division: want your
answer to have the same number of SIG FIGS
as the measurement that has the least number
of sig figs
Examples:
3 SF 7.07
1. 3.1415 x 2.25 =
2 SF 16
2. 48.2 cm x 1.6 cm x 2.12 cm =
0
22.
Calculating with sig figs
Addition and Subtraction: want your answer to
have the same number of DECIMAL PLACES as the
measurement that has the least number of DECIMAL
PLACES
1 DP 4.0
1. 6.357- 2.4 =
2 DP 28.68
2. 3.842 cm + 8.51cm + 16.324cm
cm3=
23.
- Scientific Notation
25.
AIM# 3 (b): How is the data compression
in mp3 and ZIP files mirrored in scientific
notation?
- sci notation
26.
• Comparing relative magnitudes of two
numbers in scientific notation:
27.
AIM#4: How can units be used
to solve problems? -
dimensional analysis
• To covert a measurement from one metric
unit to another, you must know the
difference in magnitude between the
two prefixes and use the to create a
conversion factor
28.
AIM: How can units be used to
solve problems? - dimensional
• Use Reference Table C. If there is no
prefix (m, g, L, etc.) then the power of
ten is 100 . The prefix is underlined so
you can verify its magnitude against
Reference Table C. The smaller unit is
italicized
29.
AIM: How can units be used to
solve problems? - dimensional
TO USE THE CONVERSION FACTOR: **NOTES: the
number of sig figs in your final answer equals the
number of sig figs in the number you are converting
•Given amount multiplied or divided by the conversion =
•If the given unit is also the numerator unit on the
conversion factor, then DIVIDE to cancel it out
•If the given unit is also the denominator unit on the
conversion factor, then MULTIPLY to cancel it out
30.
DIMENSIONAL
ANALYSIS EXAMPLES
31.
Ex 1) A pin measuring 2.85 cm in
length. What is its length in inches?
• Need an equivalence statement
2.54cm = 1in
• Divide both sides by 2.54cm
• Unit Factor
• Multiply any expression by this unit factor
and it will not change its value
32.
Ex 1) A pin measuring 2.85 cm in
length. What is its length in inches?
33.
Ex 2) A pencil is 7.00 in long. What
is the length in cm?
• Convert in cm
• Need equivalence statement 2.54cm
= 1in
• Unit Factor
35.
DIMENSIONAL ANALYSIS
and
•How to choose – look at direction of required
•in cm (need to cancel in – goes in denominator)
•cm in (need to cancel cm – goes in
36.
Ex 3) You want to order a bicycle with a
25.5in frame, but the sizes in the catalog
are given only in cm. What size should
you order?
37.
Ex 4) A student entered a 10.0-km run. How
long is the run in miles?
• km mi
• Equivalence statement 1m = 1.094yd
• Strategy first
km m yards mi
• Equivalence statements:
1km = 1000m
1m = 1.094 yd
1760yd = 1 mi
38.
Ex 4) A student entered a 10.0-km run. How
long is the run in miles?
• km m
39.
Ex 4) A student entered a 10.0-km run. How
long is the run in miles?
• m yd
40.
Ex 4) A student entered a 10.0-km run.
How long is the run in miles?
• yd mi
• Original 10.0 which has 3 sig figs so you want 3 sig
figs in your answer
41.
Ex 4) A student entered a 10.0-km run.
How long is the run in miles?
• Can combine all conversions into one step
43.
AIM # 5: How do we perform
simple calculations during
experiments
Percent Error- the measurement of the percent that the
measured value is “off” from the accepted value
• Measured value
• Accepted value
Percent error % error= measured value- accepted value x
100
accepted value
(found on table T)
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