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8 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
2
Example Problem 2-1
Using Prefixes with SI Units
How many picograms are in a gram?
The prefix pico- means 10 Ϫ12 , or 1/1000000000000. Thus, there are
10 12 , or 1,000,000,000,000, picograms in one gram.
Practice Problems
1. How many centigrams are in a gram?
2. How many liters are in a kiloliter?
3. How many nanoseconds are in a second?
4. How many meters are in a kilometer?
Derived units Not all quantities can be measured using SI base
units. For example, volume and density are measured using units
that are a combination of base units. An SI unit that is defined by a
combination of base units is called a derived unit. The SI unit for
volume is the liter. A liter is a cubic meter, that is, a cube whose
sides are all one meter in length. Density is a ratio that compares the
mass of an object to its volume. The SI units for density are often
grams per cubic centimeter (g/cm 3 ) or grams per milliliter (g/mL).
One centimeter cubed is equivalent to one milliliter.
▲
Prefixes Used with SI Units
Scientific
Prefix
Symbol
Factor
notation
Example
giga
G
1,000,000,000
10 9
gigameter (Gm)
mega
M
1,000,000
10 6
megagram (Mg)
kilo
k
1000
10 3
kilometer (km)
deci
d
1/10
10 Ϫ1
deciliter (dL)
centi
c
1/100
10 Ϫ2
centimeter (cm)
milli
m
1/1000
10 Ϫ3
milligram (mg)
micro
␮
1/1000000
10 Ϫ6
microgram (␮g)
nano
n
1/1000000000
10 Ϫ9
nanometer (nm)
pico
p
1/1000000000000
10 Ϫ12
picometer (pm)
Table 2-2