Transcript Document

International System of Units 3.2
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3.2
The International System
of Units
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Measuring with SI Units
All measurements depend on units that serve as
reference standards. The standards of
measurement used in science are those of the
metric system.
The International System of Units (abbreviated
SI, after the French name, Le Système
International d’Unités) is a revised version of the
metric system.
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3.2
The International System
of Units
>
Measuring with SI Units
The five SI base units commonly used
by chemists are the meter, the kilogram,
the kelvin, the second, and the mole.
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3.2
The International System
of Units
>
Units and Quantities
Units of Length
In SI, the basic unit of length, or linear measure,
is the meter (m). For very large or and very small
lengths, it may be more convenient to use a unit
of length that has a prefix.
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3.2
The International System
of Units
>
Units and Quantities
Common metric units of length include
the centimeter, meter, and kilometer.
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3.2
The International System
of Units
>
Units and Quantities
Units of Volume
The SI unit of volume is the amount of space
occupied by a cube that is 1 m along each edge.
This volume is the cubic meter (m)3. A more
convenient unit of volume for everyday use is the
liter, a non-SI unit.
A liter (L) is the volume of a cube that is 10
centimeters (10 cm) along each edge (10 cm 
10 cm  10 cm = 1000 cm3 = 1 L).
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3.2
The International System
of Units
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Units and Quantities
Common metric units of volume include
the liter, milliliter, cubic centimeter, and
microliter.
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3.2
The International System
of Units
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Units and Quantities
The volume of 20 drops of liquid from a
medicine dropper is approximately 1 mL.
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The International System
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Units and Quantities
A sugar cube has a volume of 1 cm3. 1 mL is
the same as 1 cm3.
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3.2
The International System
of Units
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Units and Quantities
Units of Mass
The mass of an object is measured in
comparison to a standard mass of 1 kilogram
(kg), which is the basic SI unit of mass.
A gram (g) is 1/1000 of a kilogram; the mass of 1
cm3 of water at 4°C is 1 g.
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3.2
The International System
of Units
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Units and Quantities
Common metric units of mass include
kilogram, gram, milligram, and
microgram.
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3.2
The International System
of Units
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Units and Quantities
Weight is a force that measures the pull on a
given mass by gravity.
The astronaut shown on the surface of the
moon weighs one sixth of what he weighs on
Earth.
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The International System
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Units and Quantities
Units of Temperature
Temperature is a measure of
how hot or cold an object is.
Thermometers are used to
measure temperature.
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The International System
of Units
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Units and Quantities
Scientists commonly use two equivalent
units of temperature, the degree Celsius
and the kelvin.
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Units and Quantities
On the Celsius scale, the freezing point of
water is 0°C and the boiling point is 100°C.
On the Kelvin scale, the freezing point of water
is 273.15 kelvins (K), and the boiling point is
373.15 K.
The zero point on the Kelvin scale, 0 K, or
absolute zero, is equal to 273.15 °C.
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The International System
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Units and Quantities
Because one degree on the Celsius scale is
equivalent to one kelvin on the Kelvin scale,
converting from one temperature to another is
easy. You simply add or subtract 273, as shown
in the following equations.
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Units and Quantities
Conversions Between the Celsius and Kelvin
Scales
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SAMPLE PROBLEM 3.4
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Practice Problems for Sample Problem 3.4
Problem Solving 3.17 Solve
Problem 17 with the help of an
interactive guided tutorial.
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3.2
The International System
of Units
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Units and Quantities
Units of Energy
Energy is the capacity to do work or to produce
heat.
The joule and the calorie are common
units of energy.
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The International System
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Units and Quantities
The joule (J) is the SI unit of energy.
One calorie (cal) is the quantity of heat that
raises the temperature of 1 g of pure water by
1°C.
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The International System
of Units
Prefix
Abbre.
Meaning
>
Know these and the base units
for the quiz!!!!!!
Example Conversion #1
Example Conversion #2
Tera
T
1 x 1012
1 Tm = 1 x 1012 m
or
1 x 10-12 Tm = 1 m
Giga
G
1 x 109
1 Gm = 1 x 109 m
or
1 x 10-9 Gm = 1 m
Mega
M
1 x 106
1 Mm = 1 x 106 m
or
1 x 10-6 Mm = 1 m
kilo
k
1 x 103
1 km = 1 x 103 m
or
1 x 10-3 km = 1 m
hecto
h
1 x 102
1 hm = 1 x 102 m
or
1 x 10-2 hm = 1 m
deka
da
1 x 101
1 dam = 1 x 101 m
or
1 x 10-1 dam = 1 m
deci
d
1 x 10-1
1 dm = 1 x 10-1 m
or
1 x 101 dm = 1 m
centi
c
1 x 10-2
1 cm = 1 x 10-2 m
or
1 x 102 cm = 1 m
milli
m
1 x 10-3
1 mm = 1 x 10-3 m
or
1 x 103 mm = 1 m
micro
µ
1 x 10-6
1 µm = 1 x 10-6 m
or
1 x 106 µm = 1 m
nano
n
1 x 10-9
1 nm = 1 x 10-9 m
or
1 x 109 nm = 1 m
pico
p
1 x 10-12
1 pm = 1 x 10-12 m
or
1 x 1012 pm = 1 m
base
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