Transcript Introduction to Chemistry II

Factor-Label
Method
What is it?
Factor-Label
The most important
mathematical process
in chemistry.
Treats numbers and
units equally.
Multiply what is given by
fractions equal to one
to convert units.
Factor-Label
What is given
A fraction
equal to one
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Convert 1000 grams
to pounds.
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Convert 1000 grams to pounds
1000 g
1 pound
= 2.2 pounds
454 g
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Convert 65 miles/hour
to meters/second.
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Convert 65 miles/hour to
meters/second
65 miles
hour
hour
second
meters
miles
=
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How many basketballs can
be carried by 8 buses?
1 bus = 12 cars
3 cars = 1 truck
1000 basketballs = 1 truck
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How many basketballs can
be carried by 8 buses?
8 buses
1 bus = 12 cars
3 cars = 1 truck
1000 basketballs = 1 truck
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How many basketballs can
be carried by 8 buses?
8 buses
12 cars
1 bus
1 bus = 12 cars
3 cars = 1 truck
1000 basketballs = 1 truck
Factor-Label
How many basketballs can
be carried by 8 buses?
8 buses
12 cars
1 truck
1 bus
3 cars
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How many basketballs can
be carried by 8 buses?
8 buses
12 cars
1 truck 1000 bballs
1 bus
3 cars
1 truck
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32000 basketballs can
be carried by 8 buses.
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Method
End
The
International System
of Measurement
SI Base Units
Mass - Kilogram
Length - Me te r
Time - Second
Temperature - Kelvin
Amount of substa nce - Mole
Electric current - Ampere
Light intensity - Candela
Derived Units
Combination of Base Units
Area = length2
Volume = length3
Density = mass / volume
SI Prefixes
Mega
Kilo
Deci
Centi
Milli
Micro
Nano
- 1 000 000
1 000
0.1
0 . 01
0 . 001
0 . 000 001
0 . 000 000 001
Different Volume Units
Liter = Cubic De cimeter
Milliliter = Cubic Centimeter
The
International System
of Measurement
End
Significant Digits
Significant Digits
A significant digit is one
which is actually measured.
The number of significant
digits in a measurement
depends on the ability of
the measuring device.
Significant Digits
When a calculation involves
numbers with different
s i g n i f i c a n t d i g i t s , t he
answer can have no more
significant digits than the
least used in the calculation.
Rules to determine
significant digits
1. D i g i t s o t h e r t h a n z e r o
are always significant.
2. F i n a l z e r o s a f t e r a d e c i m a l
point are always significant.
3. Z e r o s b e t w e e n t w o o t h e r
significant digits are
always significant.
4. Z e r o s u s e d o n l y t o s p a c e t h e
decimal are not significant.
Properties
Qualitative - A property
without measurements.
Quantitative - A property
is described by a number
of standard units of
measurement.
Reliability
Accuracy - How close a
measurement is to the
true value of the quantity.
Precision - How close a set
of measurements for a
quantity are to one
another, regardless of
whether they are correct.
Percent Error
Comparison of an
experimental value
to a known value.
exp value - known value
% error =
known value
Significant Digits
End
Scientific Notation
n
M X 10
Scientific Notation
Used to represent very large
or very small numbers.
There are two parts to a
number expressed in
scientific notation.
The basic form is:
n
M X 10
Part One:
M has a single digit to
the left of the decimal
with digits to the right of
the decimal representing
any other significant
digits.
n
M X 10
Part Two a:
n
is an integer
representing the number
of places to move the
decimal point.
n
M X 10
continued
Part Two b:
If n is positive move the
decimal point to the right.
The number is greater than
one.
n
M X 10
continued
If n is negative, move the
decimal point to the left.
The number is less than
one.
M X 10
-n
Write the following in
scientific notation:
60000000
6 X 10 7
0.000005
5 X 10 -6
125000
1 . 2 5 X 10 5
Scientific notation
and your calculator:
 Enter M
 EE or EXP
 Enter n
 If n is negative,
change sign
M X 10
-n
Scientific notation
and your calculator:
Enter this number in
your calculator:
6.02X10
23
Scientific notation
and your calculator:
Multiply by this number:
2 . 5 X 1 0 -5
The answer is:
1.5 X 10
19
Scientific Notation
End