Units and Calculations
The Metric System
Chemistry is an experimental science. In order for experiments to be quantitative and
reproducible we need a standard set of units. The agreed upon system of measurement in the
sciences is the
International System
, otherwise known as
S.I. Units.
S.I. stands for Le Systéme International. This is the metric system with which you may already
be familiar. The metric system is easy to learn and use because subdivisions and multiples of the
base units employ only factors of 10. Prefices indicate the size of the unit relative to the base
unit.
Prefix
Symbol
Multiple of Base Unit
mega
M
1,000,000 or 10
6
kilo
k
1,000 or 10
3
deci
d
0.1 or 10
1
centi
c
0.01 or 10
2
milli
m
0.001 or 10
3
micro
μ
0.000001 or 10
6
nano
n
10
9
pico
p
10
12
Length
The Base unit for length in the metric system is the meter. The abbreviated symbol for meters is
m. A meter is slighly longer than a yard (
i.e.,
1 m = 39.37 inches).
Volume
The Base unit for volume in the metric system is the cubic meter. The abbreviated symbol for
meters is m
3
. In practice, the cubic meter is not a convenient unit for everyday use, so the cubic
decimeter (dm
3
) is used instead. Because it is so often used 1 dm
3
is given the name liter. The
abbreviated symbol for a liter is L or l. When working with even smaller volumes the cubic
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 Winter '08
 FOUCHER
 International System of Units, Kilogram, Litre, base unit

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