What is Density?
Density (physical property):
 the amount of mass per unit volume
or
 a comparison of how much matter there
is in a specific space
 for example, a substance has a density of
3.1 g/cm3
 this means that this substance has 3.1 g
of matter in 1 cubic centimetre
DENSITY
Low Density
High Density
1 cm
1 cm
1 cm
1 cm
1 cm
1 cm
less
•The substance has _________
mass in 1 cm3.
more
•The substance has _________
mass in 1 cm3.
•The particles are packed
loosely with very ________
large
________
spaces between them.
•The particles are packed
tightly with very ________
small
________
spaces between them.
DENSITY
Low Density
Examples:
High Density
Examples:
styrofoam
metals
oil
rocks
bricks
sponge
wax
ALWAYS
REMEMBER
UNITS!
DENSITY
 Density =
mass
volume
or
D=m
V
 Units for density: g/cm3 or kg/m3
3
1g/cm
 Water has a density of ___________.
 Anything with a density > 1g/cm3
sinks
__________
in water.
 Anything with a density < 1g/cm3
floats in water.
__________
Which one is more dense?
D=8g
8 cm3
=1 g/cm3
Assume:
=1g
D = 16 g
8 cm3
= 2 g/cm3
2 cm
2 cm
2 cm
2 cm
2 cm
2 cm
Now which one is more dense?
D=5
D = 27 g
27 cm3
= 1 g/cm3
g/cm3
3 cm
1 cm
1 cm
1 cm
3 cm
3 cm
LIQUID LAYERS
 Which layer has the highest
density?
 Which layer has the lowest density?
 Imagine that the liquids have the
following densities & match them cork
to each layer:
wax
 1.40
g/cm3
 0.91
g/cm3
g/cm3
0.78
1.12 g/cm3
water
 rubber (1.38 g/cm3)
0.91 g/cm3
1.12 g/cm3
rubber
 At which layer would each of the
following float?
marble
 marble (2.6 g/cm3 )
0. 78 g/cm3
1.40 g/cm3
 wax (0.87 g/cm3)
 cork (0.05 g/cm3)
 water
WHY....?
 do ice cubes float in water?
 when water freezes the molecules
packed themselves more loosely
than the liquid state, making its
density slightly less
 do ships float if metals have a
much higher density than water?
 most of the volume of the ship is
filled with air, which has a very low
density compared to water,
lowering the average density of the
ship
APPLYING THE PRINCIPLES OF DENSITY
• submarines can alter the average density of the ship
by pumping water into large holding tanks called
ballasts
• to make the submarine rise, the water is pumped out
and air pumped into the ballasts.
• fish use a swim bladder
that they fill with air to
make them float
• they push the air out to
increase density & sink
APPLYING THE PRINCIPLES OF DENSITY
• 1st hot air balloons are partially inflated with cold air from a
gas-powered fan
•
•propane burners are used for final inflation
•heat gives air molecules in balloon more kinetic energy
•collide & move apart
•density of air in the balloon is lower than outside air
•balloon floats up
DENSITY CALCULATIONS WORKSHEET 1
1. A block of aluminum has a volume of 15 mL
and weighs 40.5 g. What is its density?




Given:
V= 15 mL
m = 40.5 g
D=?
D= m
V
= 40.5 g
15 mL
= 2.7 g/mL
 The density of the aluminum is 2.7 g/mL.
DENSITY CALCULATIONS WORKSHEET 1
3. What is the mass of ethanol that exactly
fills a 200 mL container? The density of
ethanol is 0.789 g/mL.
m




Given:
V = 200 mL
D = 0.789 g/mL
m=?
m= D V
= (0.789 g/mL)(200 mL)
= 157.8 g
 The mass of ethanol is 157.8 g.
D
V
LEARNING CHECK
What is the density (g/cm3) of 48 g of a metal
block if the metal raises the level of water in a
graduated cylinder from 25 mL to 33 mL?
1) 0.2 g/ cm3
2) 6 g/cm3
3) 252 g/cm3
33 mL
25 mL
REVIEW
 What is the formula for density?
 What happens if you pour together liquids that
have different densities?
 Will the liquid on the top have the highest or
M a s s
lowest density?
 Will the liquid on the bottom have the highest or
lowest density?
 If the yellow arrow on the
graph is water, which
colours represent
substances that will:
 sink in water?
volume
 float in water?
HOMEWORK
 Complete ‘Density Calculations Worksheet # 1’.
SUPER SCIENTIST QUESTION OF THE DAY
 You are given an empty jar, mass of
41 g. If you completely fill the jar
with water, its mass is 139 g. If you
pour the water out and fill it with
vegetable oil, the mass of the jar of
oil is 128 g. What is the density of the
oil?
Density Calculations Worksheet #1
1. Find the unknown quantity.
 a) D = 3 g/mL


V = 100 mL
m=?
 b) D = ?


V = 950 mL
m = 95 g
m = DV
= (3 g/mL)(100 mL)
= 300 g
D= m
V
= 95 g
950 mL
= 0.1 g/mL
Density Calculations Worksheet #1
1. Find the unknown quantity.
 c) D = 0.5 g/mL


V= ?
m = 20 g
V =m
D
= 20 g
0.5 g/mL
= 40 mL
2. Find the unknown quantity. (Convert 1st).
 a) D = 24 g/mL


1 200 mL
V = 1.2 L = _______
m= ?
m = DV
= (24 g/mL)(1200 mL)
= 28 800 g
28.8
= _______
kg
Density Calculations Worksheet #1
2. Find the unknown quantity. (Convert 1st).
 b) D = ?

V = 100 mL
1 500 g
m = 1.5 kg = _______
D= m
V
= 1 500 g
100 mL
= 15 g/ mL
 c) D = ?


520 mL
0.52 L = _______
V=
0.5 g
m = 500 mg = ______
D= m
V
= 0.5 g
520 mL
= 0.00096 g/ mL
= 0.001 g/mL
Density Calculations Worksheet #1
WORD PROBLEMS
2. Mercury metal is poured into a graduated
cylinder that holds exactly 22.5 mL. The
mercury used to fill the cylinder weighs
306.0 g, From this information, calculate
the density of mercury.




Given:
V= 22 .5 mL
m = 306.0 g
D=?
D=m
V
= 306.0 g
22.5 mL
= 13.6 g/mL
 The density is 13.6 g/mL.
Density Calculations Worksheet#1
WORD PROBLEMS
4. A rectangular block of copper metal weighs
1 896 g. The dimensions of the block are
8.4 cm by 5.5 cm by 4.6 cm. From this data,
what is the density of copper.





Given:
m = 1 896 g
V = 8.4 cm x 5.5 cm x 4.6 cm
3
= _______cm
212.5
D=?
 The density is 8.9 g/cm3
D=m
V
= 1 896 g
212.5 cm3
= 8.9 g/cm3
Density Calculations Worksheet #1
WORD PROBLEMS
5. What volume of silver metal will weigh
exactly 2500.0 g. The density of silver is
10.5 g/cm3.




Given:
V=?
m = 2 500.0 g
D = 10.5 g/cm3
 The volume is 238.1 cm3.
V=m
D
= 2 500.0 g
10.5 g/cm3
= 238.1 cm3
Density Calculations Worksheet #1
WORD PROBLEMS
6. Find the mass of 250.0 mL of benzene. The
density of benzene is 0.8765 g/mL.




m = DV
Given:
m= ?
= (0.8765 g/mL)(250.0 mL)
V = 250.0 mL
= 219.1 g
3
D = 0.8765 g/mL
 The volume is 219.1 cm3.
Density Calculations Worksheet #1
WORD PROBLEMS
7. A block of lead has dimensions of 4.50 cm by
5.20 cm by 6.00 cm. The block weighs 1 587 g.
From this information, calculate the density of
lead.
D=m
 Given:
V
 V = 4.50 cm x 5.20 cm x 6.00 cm
= 1 587 g
3
140.40 cm3
140.40
 = _______cm
 m = 1 587 g
= 11.3 g/cm3
 D=?
 The density is 11.3 g/cm3
Density Calculations Worksheet#1
WORD PROBLEMS
8. If 28.5 g of iron shot is added to a graduated
cylinder containing 45.50 mL of water, the
water level rises to the 49.10 mL mark. From
this information, calculate the density of iron.






Given:
m = 28.5 g
V1 = 45.50 mL
V2 = 49.10 mL
3.6 mL
= _____
D=?
 The density is 7.9 g/mL
D=m
V
= 28.5 g
3.6 mL
= 7.9 g/mL