Unit 1Introduction to Chemistry
Internet web site:
www.unit5.org/chemistry
Outline
Outline
PowerPoint Presentation by Mr. John Bergmann
Safety
Basic Safety Rules
Use common sense.
No horseplay.
No unauthorized experiments.
Handle chemicals/glassware with respect.
Others:
#1 Rule:
Safety Features of the Lab
safety showerfire blanketfire extinguishereye washfume hoodcircuit breaker switch
Material Safety Data Sheet (MSDS)
gives informationabout a chemical
-- lists “Dos” and “Don’ts;”
emergency procedures
--
Chemical Exposure
a one-time exposure causes damage
acute exposure chronic exposure
damage occurs after repeated exposure
reaction to drugs
or medicatione.g., e.g., smoking,
asbestos
the lethal dosage for 50% of the animals on which the chemical is tested
LD50
There are various ways an LD50 can be expressed. For example, acetone has the following LD50s:
ORL-RAT LD50: 5,800 mg/kgIHL-RAT LD50: 50,100 mg/m3-hSKN-RBT LD50: 20 g/kg
Example
Which is more toxic?
Chemical A is more toxic because less of it proves fatal to half of a given population.
Chemical A: LD50 = 3.2 mg/kgChemical B: LD50 = 48 mg/kg
Science
The Functions of Science
pure science applied science
the search for knowledge; facts
using knowledgein a practical way
e.g., aluminum
strong
lightweight
good conductor
Science attempts to establish cause-effect relationships.
risk-benefit analysis
weigh pros and cons before deciding
Because there are many considerations for each case, “50/50 thinking” rarely
applies.
How does scientific knowledge advance?
1. curiosity2. good observations3. determination4. persistence
The Scientific Method
** Key: Be a good observer.
observation inference
involves a judgmentor assumption
uses the fivesenses
Types of Data
Observations are also called data.
qualitative data quantitative data
clear liquid --
-- e.g., e.g.,
descriptions
measurements 55 L or 83oC
Parts of the Scientific Method
Identify an unknown.
Make a hypothesis: a testable prediction
Repeatedly experiment to test
hypothesis.
procedure: order of events in
experiment
variable: any factor that couldinfluence the result
(i.e., a recipe)
A ScientificExperiment
conclusion: must be based on the data
Experiments must be controlled:
they must have two set-ups
that differ by only one variable
Scientific Law vs. Scientific Theory
law:
Theory of Gravity,
Atomic Theory
states what happens
tries to explain why or
how something happens
-- e.g.,
does not change
law of gravity,laws of
conservation
never violated
-- --
theory:
-- e.g., -- based on current evidence
Phlogiston Theory of Burning
1. Flammable materials contain phlogiston.
2. During burning, phlogiston is released
into the air.
3. Burning stops when…
…object is out of phlogiston, or
…the surrounding air contains
too much phlogiston.
(superceded by combustion theory of burning)
Chemistry
The Beginning
The Greeks believed there
were four elements.
early practical chemistry:
household goods, weapons,
soap, wine, basic medicine
earth wind fire water
D ~~D___
D
___
Alchemy
Allegedly, this substance would turn cheap metals into gold.
the quest for the Philosopher’s Stone
(~500 – 1300 C.E.)
(the elixir, the Sorcerer’s Stone)
Alchemical symbols for substances…
. . . . . . . . . . . .
. . .
GOLD SILVER COPPER IRON SAND
transmutation:
we cannot
transmute elements into different elements.
changing one substance
into another
COPPER GOLD
Philosopher’s
Stone
In ordinary chemical reactions…
Alchemy was practiced in many regions of the
world, including China and the Middle East.
Alchemy arrived in western Europe
around the year 500 C.E.
Modern chemistry evolved from alchemy.
Contributionsof alchemists:
• experimental techniques• new glassware• information about elements• developed several alloys
What is Chemistry?
the study of matter
and its changes
Areas of Chemistryorganic
physicalinorganic
biochemistry
studies everything
except carbon
e.g., compounds
containing metals
the study of carbon-
containing
compounds
measuring physicalproperties ofsubstances
the chemistry ofliving things
e.g., the melting point of gold
Careers in Chemistry
• research (new products)• production (quality control)• development (manufacturing)• chemical sales• software engineering• teaching
The skills you will develop by an earnest
study of chemistry will help you in any
career field.
The Scope of Chemistry
pharmaceuticals
nylon, polyester, rayon
bulk chemical manufacturing
petroleum products
synthetic fibers
acids, bases, fertilizers
fuels, oils, greases, asphalt
1 in 10,000 new products gets FDA approval
spandex,
**sulfuric acid (H2SO4) = #1 chemical
All fields of endeavor
are affected by chemistry.
Government Regulation of Chemicals
The government
regulates chemicals
to protect the…OSHAworker
FDA
USDA
FAA
CPSC consumer
EPA
environment
Manipulating Numerical Data
Graphs
Bar Graphshows how many of something
are in each category
0
2
4
6
8
10
A B C D F
Chemistry Grades
# o
f st
ud
ents
Pie Graph shows how a whole is broken into parts
Entertainment (40%)
Food (25%)
Clothing (20%)
Savings (15%)
Percentage ofWeekly Income
Line Graphshows continuous change
0
10
20
30
40
50
60
Jan Feb Mar Apr
Month
Sh
are
Pri
ce (
$)
Stock Price over Time
you will always use a line graph. In chemistry…
Elements of a “good” line graph
2. axes labeled, with units
Temp. v. Vol. for a Gas at Constant Pressure
0123456789
10
120 140 160 180 200 220 240
Temp. (K)
Vo
lum
e (
L)
4. use the available space
1. title
3. neat
Essential Math of Chemistry
Scientific Notation-- used to express very large or very small
numbers, and/or to indicate precision(i.e., to maintain the correct number
of significant figures)
Form: (# from 1 to 9.999) x 10exponent
800 = 8 x 10 x 10
= 8 x 102
2531 = 2.531 x 10 x 10 x 10
= 2.531 x 103
0.0014 = 1.4 10 10 10
= 1.4 x 10–3
Put in standard form.
1.87 x 10–5 = 0.0000187
3.7 x 108 = 370,000,000
7.88 x 101 = 78.8
2.164 x 10–2 = 0.02164
Change to scientific notation.
12,340 = 1.234 x 104
0.369 = 3.69 x 10–1
0.008 = 8 x 10–3
1,000,000,000 = 1 x 109
6.02 x 1023 = 602,000,000,000,000,000,000,000
Using the Exponent Key
EXP
EE
The EE or EXP or E key means “times 10 to the…”
How to type out 6.02 x 1023:
6 EE. 0 32 2
6 y x. 0 32 2
x 16 . 0 2 EE 320
y x 32x 16 . 0 2 0
not…
or…
and not…
How to type out 6.02 x 1023:
6 EE. 0 32 2
WRONG!
WRONG!
TOO MUCH WORK.
Also, know when to hit your (–) sign.
(before the number,
after the number,
or either one)
4.3 x 10–9 4.3 E –9or
1.2 x 105 2.8 x 1019
But instead is written…
=
1 . 2 EE 5
92 . 8 EE 1
Type this calculation in like this:
This is NOT written… 4.3–15
4.2857143 –15Calculator gives…
4.2857143 E–15or…
–6.5 x 10–19
5.35 x 103 or 5350
2.9 x 1023
7.5 x 10–6 (–8.7 x 10–14) =
4.35 x 106 (1.23 x 10–3) =
5.76 x 10–16 9.86 x 10–4 =
8.8 x 1011 x 3.3 x 1011 =
5.84 x 10–13
Essential Mathof Chemistry
Units must be carried into the
answer, unless they cancel.
0.64 kg-ms2
5.2 kg (2.9 m)
(18 s)(1.3 s)=
4.8 kg (23 s)
(18 s)(37 s)= 0.57 kg
s
Solve for x. x + y = z
x + y = z – y – y
x = z – y
x and y are connected by addition. Separate them using subtraction. In general, use opposing functions to separate things.
The +y and –y cancel on the left,
leaving us with…
Solve for x. x – 24 = 13
x – 24 = 13 +24 +24
x = 37
x and 24 are connected by subtraction. Separate them using the opposite function: addition.
The –24 and +24 cancel on the left,
leaving us with…
Numerical Example
Solve for x. F = k x
F = k xk k
x = Fk __
x and k are connected by multiplication. Separate them using the opposite function: division.
( )__1k
F = k x( )__1k
(or)
The two k’s cancel on the right,
leaving us with…
Numerical Example
Solve for x. 8 = 7 x
8 = 7 x7 7
x and 7 are connected by multiplication. Separate them using the opposite function: division.
( )__17
8 = 7 x( )__17
(or)
The two 7’s cancel on the right,
leaving us with…x =
87 __
Solve for x. ___ x
BA = TRH
___
BAH = xTR
One way to solve this is to cross-multiply. BAH = xTR
Then, divide both sides by TR.
The answer is… ___BAHTR
x =
1TR( )___1
TR( )___
Solve for T2, where…
P1 = 1.08 atm
P2 = 0.86 atm
V1 = 3.22 L
V2 = 1.43 L
T1 = 373 K
P1V1T2 = P2V2T1
____ T1
P1V1 = P2V2
T2
____
1P1V1
( )____ 1P1V1
( )____
T2 = P1V1
______P2V2T1
132T2 = (1.08 atm)(3.22 L)_____________________(0.86 atm)(1.43 L)(373 K)
= K
SI Prefixes
kilo- (k) 1000
deci- (d) 1/10
centi- (c) 1/100
milli- (m) 1/1000
Also,
1 mL = 1 cm3 and 1 L = 1 dm3
Conversion Factorsand
Unit Cancellation
How many cm are in 1.32 meters?
conversion factors:
equality:
or
1.32 m = 132 cm
1 m = 100 cm
______1 m100 cm
We use the idea of unit cancellation
to decide upon which one of the two
conversion factors we choose.
______1 m
100 cm
( )______1 m
100 cm
(or 0.01 m = 1 cm)
How many m is 8.72 cm?
conversion factors:
equality:
or
8.72 cm = 0.0872 m
1 m = 100 cm
______1 m100 cm
Again, the units must cancel.
______1 m
100 cm
( )______1 m100 cm
How many kilometers is 15,000 decimeters?
15,000 dm = 1.5 km( )____1,000 m
1 km10 dm
1 m ( )______
How many seconds is 4.38 days?
= 378,432 s1 h
60 min24 h1 d 1 min
60 s____( ) ( )____( )_____4.38 d
3.78 x 105 sIf we are accounting for significant figures, we would change this to…
Simple Mathwith
Conversion Factors
Find area of rectangle.
A = L . W
= (4.6 cm)(9.1 cm)
9.1 cm= 42 cm2 . cm
4.6 cm
Convert to m2. 42 cm2 ( )______100 cm
1 m 2 = 0.0042 m2
Convert to mm2. 42 cm2 ( )______ 1 cm10 mm 2 = 4200 mm2
cm.cm
For the rectangular solid:
Find volume.
Length = 14.2 cm
Width = 8.6 cm
Height = 21.5 cm
V = L . W . H
= (14.2 cm)(8.6 cm)(21.5 cm)
= 2600 cm3
Convert to mm3.
2600 cm3 ( )______ 1 cm10 mm 3 = 2,600,000 mm3
= 2.6 x 106 mm3
mm and cm differ by a factor of……….
mm2 “ cm2 “ “ “ “ “ ……….
mm3 “ cm3 “ “ “ “ “ ……….
10
100
1000
Basic Concepts in Chemistry
chemical: any substance that takes part in,
or occurs as a result of,
a chemical reaction
All matter can be considered to be
chemicals or mixtures of chemicals.
chemical reaction: a rearrangement ofatoms such that…
“what you end up with”
differs from
“what you started with”
products
reactants
methane + oxygen
+ H2O(g)
carbondioxide
O2(g) CO2(g)CH4(g) +
water+
22
NaOH(aq)
water
Na(s) H2O(l) H2(g) 2
sodium
2 2
hydrogen sodiumhydroxide
+ +
+ +
Law of Conservation of Mass
total mass total mass
of products of reactants
Pmass = Rmass
=
synthesis: taking small
molecules and putting
them together, usually
in many steps, to make
something more complexJENNY
How many feet is 39.37 inches?
applicable conversion factors:
equality:
or
X ft = 39.37 in =
1 ft = 12 in
______1 ft 12 in
Again, the units must cancel.
( )____ 3.28 ft1 ft12 in
______1 ft
12 in
Lab – introduction to qualitative analysis
Resources - Intro. to ChemistryWorksheet - vocabulary
Worksheet - material safety data sheet (acetone)
Activity - checkbook activity
Worksheet - graphing
Worksheet - real life chemistry
Worksheet - conversion factors
Worksheet - scientific notation
Worksheet - metric article (questions)
Worksheet - significant digits
Worksheet - math review
Worksheet - math of chemistry
Outline (general)
Worksheet - article on the metric system Textbook - questions
Episode 1 - The World of Chemistry
Episode 4 - Modeling The Unseen
Episode 3 – Measurement: The Foundation of Chemistry