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Chem 152
May 24, 2010
Scientific Method
Develop a hypothesis: what you expect the result to be
Experiment/Observation
Conclusion on the basis of your findings/results
Was your hypothesis verified or not?
Numbers are exponential.
.. (X×10
x
)
3752.6 = 3.752 × 10
3
0.00046 = 4.6 × 10
4
Rules for exponents
Whenever you add or subtract exponential numbers, you must solve for each side of the equation before completing the
function:
2
2
+ 4
3
= 4 + 12 = 16
Whenever you multiply exponential numbers, you add the exponents: y
2
× y
2
= y
4
Whenever you divide two exponential numbers, you subtract the exponents: x
2
÷ x
2
= x
0
= 1 as long as x
≠
0
Whenever you raise an exponent expression to a power, you multiply the exponents:
(x
2
)
4
= x
8
Significant Figures
Zeroes before any number from 1
–
9 don’t count as
significant figures
Zeroes after any rational number are counted as significant figures
These rules apply only to calculations and not measurements
For measurements, your result is only limited by the precision of your equipment
When performing addition pr subtraction, the result may only have as many digits after the decimal point as the number
in the calculation with the least number of digits after the decimal point.
When performing multiplication or division, the result may contain only as many significant figures as the least precise
number in the calculation
.0072 or 7.2 × 10
3
= 2 significant figures
0.051 + 71.3
 5.853 + 100.6 = 166.098 OR 166.1
3.051 × .51 × 0.007 ÷ 61.5 = 1.7710668293, but since the number with the least significant figures in the calculation is 0.007
with one significant number, the quotient can only have one so we round to 2 × 10
4
If you move the decimal to the left
, the exponent is
positive
. 4000 = 4 × 10
3
If the decimal is moved to the right
, the exponent is
negative
.
.0004 = 4 × 10
4
o
However, this is for numbers that are
NOT
in exponential form!
o
If they are in exponential form, the opposite holds true (+ exponent moves decimal to right and  moves to left)
Units of measurement
British
Metric
Length
Foot
Meter
Mass
Pound
Gram
Time
Second
Second
Volume
Gallon
Liter
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View Full DocumentInternational System of Units (SI) prefixes:
Prefix
Symbol
10
n
Decimal
yotta
Y
1 × 10
24
1000000000000000000000000
zetta
Z
1 × 10
21
1000000000000000000000
exa
E
1 × 10
18
1000000000000000000
peta
P
1 × 10
15
1000000000000000
tera
T
1 × 10
12
1000000000000
giga
G
1 × 10
9
1000000000
mega
M
1 × 10
6
1000000
Million
kilo
k
1 × 10
3
1000
Thousand
hecto
h
1 × 10
2
100
Hundred
deca
da
1 × 10
1
10
Ten
1 × 10
0
1
One
deci
d
1 × 10
−1
0.1
Tenth
centi
c
1 × 10
−2
0.01
Hundredth
milli
m
1 × 10
−3
0.001
Thousandth
micro
μ
1 × 10
−6
0.000001
Millionth
nano
n
1 × 10
−9
0.000000001
pico
p
1 × 10
−12
.000000000001
femto
f
1 × 10
−15
.000000000000001
atto
a
1 × 10
−18
.000000000000000001
zepto
z
1 × 10
−21
.000000000000000000001
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 Summer '10
 Purandare
 Chemistry

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