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INTRODUCTION TO CHEMISTRY

WHAT IS CHEMISTRY ?

WHAT IS SCIENCE VS TECHNOLOGY ?
SCIENCE:
TECHNOLOGY:

IS "CHEMISTRY" SCIENCE OR TECHNOLOGY ?

WHAT SKILLS DO YOU NEED TO SUCCEED?
1.
2.
3.
4.
The
Scientific Method
Units
and
Conversions
Safety and
Laboratory
Equipment
Unit 1
Chemistry Tool Box
(Foundations of
Chemistry)
Exponential
Notation
Classification
of
Matter
Significant Digits
and
Measurement
Precision,
Accuracy and
% Error
Algebraic
Manipulations
Algebraic Manipulations
A.
You can add, subtract, multiply or divide as long as you carry out the operation on both sides of the
equation. For example, solve for "x" (i.e., get "x" by itself) for the following:
2x + 4 = 8
3xz = yw
First step, subtract 4:
First step, divide by z:
2x + 4 = 8
3xz = yw
z
z
2x + 4 - 4 = 8 - 4
3x = yw
z
2x = 4
Second step, divide by 3:
Second step, divide by 2:
2x = 4
2x = 4
2
2
x = 2
3x = yw
z
3x = yw
3
3z
x = yw
3z
Algebra Manipulation Practice - Solve for x. Show your work and draw a box around your answer.
1.
2x + 8 = 0
2.
3.
4(4x + 3) = - 4
4.
5.
3x - 1 = 2
4
6.
7.
1x + 1x = 5
2
3
4x + 8 = 4
3
4
3x
=
6
x + 9 - 4x = 6
5
B. You must know how to compute using a four-function calculator. The rules are simple:
1. All numbers in the numerator (numbers on top of line) are multiplied together.
2. Each number in the denominator (numbers on bottom of line) are divided into the numerator.
3. As an example, to compute the following:
45 x 96
18 x 4
= ?
Multiply 45 by 96, divide the result (4320) by 18 (result is 240), and finally, divide the 240
by 4 to get 60 [45 x 96  18  4 = 60].
Calculator Practice – Using a 4 Function Calculator, Find the Answer
1.
92 x 42
14
=
3.
31 x 62 feet =
89 x 2
2.
16 cm x 8 cm x 6 cm =
9x2x3
4.
14 x 1000 x 10
100 x 100 x 10
=
C. Simplify, simplify, simplify. For example, cancel any numbers or units that are both in the numerator or
the denominator of an expression. In other words, units cancel just like variables or numbers in an
algebraic equation.
36 eggs
X
1 dozen
12 eggs
= 3 dozen
For simplicity, chemists often omit the parenthesis and the multiplication sign. For example:
36 eggs
1 dozen
12 eggs
= 3 dozen
Simplification Practice – Simplify the Following Expressions
1.
2 (12 – 15d) =
3
3.
427 cm
__1 m__
100 cm
1000 mm
1m
5.
12 a b2 c
2abc
7.
(2 cm) (4 cm) (6 cm)
=
=
=
2.
427 cm
__1 m__
100 cm
4.
29 mm
__1 m__
1000 mm
6.
(2a) (4a) (6a) =
8.
3a
2b
100b
2c
_1d_
10a
=
100 cm
1m
=
_1 inch
2.54 cm
=
Scientific Notation
A. Scientific notation is a shorthand for clumsy numbers.
Example: 602,200,000,000,000,000,000,000 vs. 6.022 x 1023
B. Procedure involves:
1. For numbers > 10, move decimal to the left to get a positive exponent.
48,002 meters = 4.8002 x 104 meters
2. For numbers <1, move decimal to the right to get a negative exponent.
0.000476 kilograms = 4.76 x 10-4 kilograms
3. Convert the numbers to scientific notation or back to expanded (“normal”) numbers:
520 feet
1.95 x 105
0.968 meters
2.3 x 10-7
5,601 seconds
4.67 x 103
0.0043 grams
3.564 x 10-2
C. To multiply numbers expressed in scientific notation, multiply the factors and add the exponents.
For example: (5.0 x 103 ) (3.0 x 10 7) = 15 x 10 (7
+ 3)
= 15 x 1010 = 1.5 x 10 11
D. To divide numbers expressed in scientific notation, divide the factors and subtract the exponents.
16.0 x 1012 = 4.0 x 10 (12
4.0 x 103
Exponential Notation Practice
For example:
1.
10.2 x 10-6
3.6 x 103
3.
6 x 104 x 3 x 10-2
2 x 103
=
=
- 3)
= 4.0 x 109
2.
5.0 x 103 x 3.0 x 10 7 =
4.
5 x 103 x 4 x 105 =
1.0 x 10-3
Units and Conversions--Dimensional Analysis
A. What is it?
A process for converting a measurement (such as a length in meters)
to another unit (such as a length in centimeters) using conversion factors.
B. What do you need to know?
Knowledge of SCIENTIFIC UNITS and
CONVERSION FACTORS!!
1. Scientific Units are the units used by most scientists to make
measurements in the laboratory. They include:
Quantity Measured
Length
Volume
Mass
Time
Temperature
Unit
meter
liter
gram
sec
Kelvin
Unit Symbol
m
L
g
s
K
2. Examples of Conversion Factors include:
12 eggs = 1 dozen
100 centimeters = 1 meter
3. The Good News:
SI units (ones used in scientific measurement) are based on the use of
prefixes with specific definitions. These are the ones you need to know!
Prefix
kilo
centi
milli
micro
Symbol
k
c
m
µ
4. So, for length which is measured in meters (m)
1 km = 1000 m
1000 mm = 1 m
100 cm = 1m
1,000,000 μm = 1m
5. So, for volume which is measured in liters (L)
1 kL = 1000 L
1000 mL = 1L
100 cL = 1L
1,000,000 μL = 1L
6. So, for mass which is measured in grams (g)
1 kg = 1000 g
1000 mg = 1 g
100 cg = 1g
1,000,000 μg = 1 g
7. So, for time which is measured in seconds (s)
1 ks = 1000 s
1000 ms = 1 s
100 cs = 1 s
1,000,000 μs = 1 s
Practice the Following Conversions:
1.
454 kg

g
Since 1 kg = 1000g, write the equivalence as a fraction putting the "kg part" of
the conversion factor on the "bottom" as the denominator. Work shown below:
454 kg
1000g = 454000 g = 4.54 x 10 5 g
1 kg
2.
0.21 cm 
3.
14 µs  min
4.
7.4 mg  kg
m
8. So, for temperature the conversion involves the definition: K = ºC + 273 and ºC = K - 273
100 º C + 273 = 373 K
and 40 K -273 K = -233 º C