Honors Chemistry
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Unit 1: Introduction to Chemistry
Safety
Basic Safety Rules
#1 Rule:
Others:
Safety Features of the Lab
Material Safety Data Sheet (MSDS)
--- lists Dos, Don’ts, and emergency procedures
Chemical Exposure
acute exposure
vs.
chronic exposure
e.g.,
e.g.,
LD50: the lethal dosage for 50% of the animals on which the chemical is tested
Example:
Chemical A: LD50 = 3.2 mg/kg
Chemical B: LD50 = 48 mg/kg
Which is more toxic?
1
Science
The Functions of Science
pure science
applied science
e.g., aluminum
e.g.,
Science attempts to…
risk-benefit analysis:
How does scientific knowledge advance?
1.
3.
2.
4.
The Scientific Method
** Key:
observation
Types of Data
inference
qualitative data
quantitative data
--
--
e.g.,
e.g.,
Parts of the Scientific Method
Identify something you don’t know.
Make a hypothesis:
Experiment to test hypothesis.
procedure: the order of events in an experiment
variable:
Experiments must be controlled.
conclusion:
2
Scientific Law vs. Scientific Theory
law:
-- Laws are often written in the form of…
-- e.g.,
theory:
--- e.g.,
Phlogiston Theory of Burning
1. Flammable materials contain phlogiston.
2. During burning, phlogiston is released into the air.
3. Burning stops when…
…
…
Chemistry
The Beginning
early practical chemistry:
The Greeks believed
there were four elements.
Alchemy (~500 – 1300 A.D.)
the quest for the Philosopher’s Stone
..
.
. ..... .
Alchemical symbols for substances…
3
transmutation:
In ordinary chemical reactions…
Contributions of alchemists:
What is chemistry?
Areas of Chemistry
organic: the study of ______-containing compounds
inorganic: studies everything except ______ (e.g., compounds containing ______)
biochemistry: the chemistry of…
physical: measuring physical properties of substances
e.g.,
Careers in Chemistry
research
software
production
engineering
development
teaching
chemical sales
The skills you will develop by an earnest study
of chemistry will help you in any career field.
The Scope of Chemistry
bulk chemical manufacturing
pharmaceuticals
petroleum products
synthetic fibers
Chemistry impacts: --4
Government Regulation of Chemicals
The various levels of government regulate chemicals to protect the:
environment
consumer
worker
Manipulating Numerical Data
CHEMISTRY GRADES
Graphs
Bar graph:
# OF
STUDENTS
Pie graph:
9th
30%
10th
26%
11th
23%
12th
21%
A B C D F
% OF STUDENTS IN
EACH GRADE
AT NCHS
COST OF CONCERT TICKET OVER TIME
Line graph:
COST OF
CONCERT
TICKET ($)
** In chemistry…
YEAR
Elements of a “good” line graph:
1.
3.
2.
4.
Essential Math of Chemistry
Scientific Notation
-- used to express very large or very small numbers,
and/or to indicate precision. Also can be used to maintain correct sig figs.
Form:
800 =
2531 =
0.0014 =
5
EX.
Put in standard form.
EX.
1.87 x 10–5 =
7.88 x 101 =
3.7 x 108 =
2.164 x 10–2 =
Change to scientific notation.
Using the Exponent Key
12,340 =
0.008 =
0.369 =
1,000,000,000 =
The EE or EXP or E key means “times 10 to the…”







not…




yx


or…




X









X


yx




How to type out 6.02 x 1023:
and not…
Also, know when to hit your (–) sign.
1.2 x 105

EX.




 2.8 x 1019 =




7.5 x 10–6 (–8.7 x 10–14) =
5.76 x 10–16
4.35 x 106 (1.23 x 10–3) =



 9.86 x 10–4 =
8.8 x 1011 x 3.3 x 1011 =
Accuracy and Precision
All numerical data are the result of uncertain measurements.
precision: a measure of the degree of fineness of a measurement; it depends on the
extent to which the instrument is calibrated
e.g.,
When repeated, precise measurements yield similar answers each time.
precise…
e.g.,
imprecise…
accuracy:
Three types of error can affect accuracy.
human error:
-- minimize with repeated measurements
method error:
e.g., parallax in measuring with a meter stick
6
instrument error:
e.g., bathroom scale that reads 5 lbs. too heavy
Significant Figures (SF)
A student is combining separate water samples, all of differing volumes, into one large bucket.
Samples A, B and C are 25 mL, 16.37 mL and 50 mL, respectively. Once combined, what is
the total volume of all the samples?
Measurement and Precision


A (25 mL)
B (16.37 mL)
C (50 mL)
Identifying a number as a SF
 Counting SF’s in a number
o
Non-zero numbers:
o
Zeroes
o

Left:

Middle:

Right:

w/ decimal point:

w/o decimal point:
Exact Numbers

Counts

Constants

Conversion Factors
 How many SF?
25 g
0.12 kg
0.030 kg
1240560. cm
1.240560 x 106 mg
6000000 kg
6 x 104 sec
6.00 x 106 kg
246.31 g
409 cm
20.06 cm
29.200 dm
1.050 m
0.02500 g
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Sig Figs with calculations
Note:

Addition/Subtraction
o
11.31 + 33.264 + 4.1 =

Multiplication/Division
o
5.282 x 3.42 =
Back to the original question… A student is combining separate water samples, all of differing
volumes, into one large bucket. Samples A, B and C are 25 mL, 16.37 mL and 50 mL, respectively.
Once combined, what is the total volume of all the samples?
EX.
Round each to the correct number of significant figures.
Calculator
says…
75.6
2 sig. figs.
3 sig. figs.
5 sig. figs.
0.528396
387600
4200
8.4845E–4
Mathematics Review
Units must be carried into the
answer, unless they cancel.
Solve for x.
xyz
5.2 kg (2.9 m)

18 s (1.3 s)
4.8 g (23 s)

18 s (37 s)
Fk x
B A TR

x
H
8
SI Prefixes
kilo-
(k)
centi-
(c)
deci-
(d)
milli-
(m)
Also, 1 mL = 1 cm3 and 1 L = 1 dm3
Conversion Factors and Unit Cancellation
EX.
How many cm are in 1.32 meters?
equality:
conversion factors:
EX.
How many m is 8.72 cm?
EX.
How many kilometers is 15,000 decimeters?
EX.
How many seconds are in 4.38 days?
Simple Math with Conversion Factors
EX.
For the rectangular solid:
L = 14.2 cm
W = 8.6 cm
Find volume.
Convert to mm3.
mm and cm differ by a factor of……..
mm2 “
cm2 “
“ “
“
“ ……..
mm3 “
cm3 “
“ “
“
“ ……..
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H = 21.5 cm
Basic Concepts in Chemistry
chemical:
chemical reaction: a rearrangement of atoms such that…
“what you end up with”
methane
+
oxygen

sodium
+
water

differs from
“what you started with”
Law of Conservation of Mass:
synthesis: putting simpler substances together, usually in
many steps, to make something more complex
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