DENSITY
REMEMBER TO USE PLUS
WHAT
IS IT?
• A measure of how
closely the mass of a
substance is packed in a
given volume
• Physical property
• Mass per unit of volume
of a substance
• Density= mass (g)
volume (cm³)
TRY THESE
PROBLEMS
M
D
V
1. A substance has a
volume of 2.0 cm₃ and
a mass of 38.6 g.
What is the density?
2.If 17g of brass occupy
2 cubic centimeters,
what is the density?
ANSWERS
1. A substance has a volume
of 2.0 cm₃ and a mass of
38.6 g. What is the density?
• D=M/V
• Mass=38.6g
• Volume= 2 cm ₃
• D=38.6g/2 cm ₃
• D=19.3 g/cm ₃
ANSWERS
2. If 17g of brass occupy 2 cubic
centimeters, what is the
density?
• D=M/V
• Mass=17g
• Volume=2 cm ₃
• D= 17g/2cm₃
• D=8.5g/cm₃
SPECIFIC
GRAVITY
• Compare the density of a substance
with the density of water (always 1)
• Specific gravity= density of substance
density of water
• Example: specific gravity of steel
= 7.8g/ cm₃
1.0 g/ cm₃
= 7.8 (steel is 7.8 times more dense
than water)
- If the specific gravity is less than 1,
the object floats!
DENSITY
BLOCKS
Substance
Density (g/cm₃)
Acrylic
Aluminum
Brass
Copper
Oak
Pine
Polypropylen
e (plastic)
PVC
Steel
Water
1.0-1.5
2.5-2.9
8.3-8.7
8.7-9.1
0.5-0.9
0.3-0.5
0.8-0.97
1.2-1.6
7.7-8.1
1.0
SO WHAT’S
GOING ON?
• What will happen when a raw egg is
placed in regular water? What will
happen when it is placed in salt
water?
• What will happen when to a lemon
and a lime if placed in water?
• What will happen if the rind of the
lemon and lime are removed and
placed in water?
SO WHAT’S
GOING ON?
• Egg in fresh water: an object
that is more dense than water
will sink
• Egg is salt water: salt is more
dense than regular water and it
can hold up the egg
• Salt ions bind with water
molecules allowing the salt
water to become more dense
(increasing the amount of
matter per space)
LEMONS AND
LIMES?
• Lemon: floats
• Lime: sinks
• Lemon without rind: still
floats
• Lime without rind: still sinks
• Mass of lemon:
• Mass of lime:
• Volume of lemon:
• Volume of lime: