UNIT 2.2
SI UNITS/METRIC CONVERSIONS
SI UNITS


SI = International system of metric units.
Base unit = all other units are multiples of base
units or combinations)
Quantity
length
mass
time
amount of substance
Written unit
Symbol
SI UNITS
2. MULTIPLES OF BASE UNITS (p.17)
Prefix
Symbol
Exponential
mega
kilo
deci
centi
milli
micro
M
k
d
c
m
μ
106
103
10-1
10-2
10-3
10-6
 106
 103
 10-1
 10-2
 10-3
 10-6
2.2 SI UNITS
3. IMPORTANT EQUIVALENCES
1
mL = 1 cm3
1
m3 = 103 L
1
t = 103 kg
2.2 SI UNITS
Example:
 Re-write the expression “6 kilograms”
The prefix symbol for kilo is ___
 The unit symbol for grams is ___
 6 kilograms =

The exponential equivalent to kilo is ____
 6 kilograms =

METRIC CONVERSIONS

Metric conversions involve using unit
conversions between prefix symbols and
exponential equivalents.
Example:
 Write a conversion statement between cm and m.
METRIC CONVERSIONS
Write conversion statements between each of the
following

dm and m

cL and L

dmol and mol
METRIC CONVERSIONS
How many milligrams are in 5 kg?
5 kg = ? mg
No direct link between kilo and milli
What to do?


Convert to a base unit first !
METRIC CONVERSIONS
Express 7µm in Megametres
 7µm =? Mm

METRIC CONVERSIONS
How many decilitres in 0.5kL?
TRY

0.052 GHz = ? kHz
Hz is Hertz( a frequency unit)
MULTI CONVERSION
Convert 1cg/ mL into dg/L
MULTI CONVERSION
T
TRY: Convert 3 mg/L into µg/mL
METRIC CONVERSIONS
DERIVED QUANTITIES

Derived quantity =

Derived unit =
DENSITY
Density is an example of a derived unit
 What is density?


Density =
DERIVED UNITS: DENSITY

Given that a 2.44 cm3 sample of an element has a mass
of 47.14 g. Determine the density of the element.
DERIVED UNITS

Find the volume of a block of wood that has a
mass of 34.5 grams. The density of this wood is
12g/cm3
DENSITY
The density of carbon dioxide at standard
temperature and pressure is 1.96 g/L. Calculate the
mass of a 600 mL sample of carbon dioxide.
The density of air is about 1.29 g/L at standard
temperature and pressure. Would carbon dioxide tend
to rise up or sink down in the atmosphere?
_______________
Homework

Hebden Page19 #13, 14, 15(a,c,d,f,g,i),
Page 21 #16 (a,c,e)
#17 (b,d,f,h,j,L,n)
#18(a, b, c)
Page 26 # 31,33, 37