Density
Go through the powerpoint and take notes on
the back of your Density Webquest.
Which do you think would have the
greater volume and mass?
Why?
 1 kg of feathers
 1 kg of rock
What the heck is density?
Density is a measure of the “compactness”
of particles
Density is how much matter is crammed
into a certain space.
Density is NOT the same as weight.
Here’s an analogy
 Have you ever gone on vacation and been
sucked into buying all of those tacky souvenirs?
And then you pack to go home and your
suitcase will barely hold it all?!
 Your suitcase has just become more dense than
when you left home – it has
more stuff crammed into the
same space.
Give me some examples – I don’t get it.
 Batteries feel dense because they have a lot of
metal packed tightly inside.
I’m
more
dense
than
You!
 A wooden block is about the same size (volume)
as a 9 volt battery, but it feels much lighter
because there are not as many particles inside.
Give me some examples – I don’t get it.
 Chocolate feels dense because it has a lot of
sugar packed tightly inside.
I’m
more
dense
than
You!
 A marshmallow that is about the same size
(volume) as the chocolate feels much lighter
because there are not as many particles inside.
Some of the particles are even air bubbles!
Give me some examples – I don’t get it.
Give me some examples – I don’t get it.
In MATH language…
Density is the amount of mass an
object has compared to its volume
or
Density =
mass
volume
For Math Phobics….
A way to determine relative density it to
do the old floater / sinker test.
Water has a density of 1 g/mL.
If something floats in water, it has a
density less than 1 g/mL.
If something sinks in water, it has a
density of greater than 1 g/mL.
Do all rocks sink?
Does all wood float?
See? You already…
LOVE
density!
I love it so much…
Sometimes I even draw a heart and shoot
an arrow through it when I am
daydreaming about density.
Back to the formula…
If you squint your eyes, this sorta looks
like an
m
v
Back to the formula…
Your mind is now forever corrupted – you
won’t be able to see a cupid’s heart
without thinking about density 
Now, let’s put the formula to use…
The m stands for mass.
What is mass?
Mass is the amount of particles
(matter) in something.
 Here on earth, that kinda means how much it weighs, since
the location is all the same.
Now let’s put the formula to use
To find the mass, use a triple beam
balance.
Or a digital scale
Now let’s put the formula to use…
 What is the measurement reading on this triple beam
balance?
100 + 60 + 3.7 grams = 163.7 grams
Now let’s put the formula to use,
The V stands for volume.
What is volume?
Volume is the amount of space
that something takes up.
Now let’s put the formula to use…
To find the volume of a cubic shape, use a
centimeter ruler.
Notice that there are no markings for ½ or
¼ etc. Each little line is 0.1 centimeters.
Now let’s put the formula to use…
To find the volume of something irregular
(doesn’t have a perfect cubic shape) use
the water displacement method with a
graduated cylinder
or an overflow can.
Now let’s put the formula to use,
1- Put some water in the graduated
cylinder and make a note of how much is
in there.
2- Drop in the thing you want to measure.
3- Make a note of the new water level
reading.
4- Find the CHANGE in water level by
subtracting.
Now let’s put the formula to use…
What is the measurement reading on this
graduated cylinder?
 Read from the bottom of the meniscus (the
curved bubble thing)
 52 milliliters or 52 ml
Volume UNITS……
1 cubic centimeter =
1
3
cm
= 1 cc =1 mL
Now let’s put the formula to use…
Calculate the density of water.
(Remember to find the mass of the
container first.)
To find the density
1 - Find the mass of the object
2- Find the volume of the object
3- Divide them
Density =
m
=
v
482.63 g
≈
2.4
g
/
mL
200 mL
Units for density g/cm3 or g/ml
Formula:
M = mass V= volume D = density
M=DxV
V=M/D
D=M/V
To find density:
1)
Find the mass of the object
2)
Find the volume of the object
3)
Divide : Density = Mass
Volume
Ex.
If the mass of an object is 35 grams and
it takes up 7 cm3 of space, calculate the
density.
To find density:
1)
Find the mass of the object
2)
Find the volume of the object
3)
Divide : Density = Mass
Volume
Ex.
If the mass of an object is 35 grams and
it takes up 7 cm3 of space, calculate the
density.
Set up your density problems like this:
Given: Mass = 35 grams
Formula: D =
M
V
Volume = 7 cm3
Unknown: Density (g/ cm3)
Solution: D = 35 g
7 cm3
D = 5 g/cm3
LIQUID LAYERS
Liquid Layers
If you pour together liquids that don’t mix
and have different densities, they will form
liquid layers.
The liquid with the highest density will be
on the bottom.
The liquid with the lowest density will be
on the top.
Steve
Spangler
7 layer
density
Learning Check
Which diagram correctly represents the liquid layers
in the cylinder? Karo (K) syrup (1.4 g/mL), vegetable
(V) oil (0.91 g/mL,) water (W) (1.0 g/mL)
1
2
3
V
W
W
K
K
V
K
V
W
38
Solution
1)
V
Vegetable oil 0.91 g/mL
W
K
Water 1.0 g/mL
Karo syrup 1.4 g/mL
39
Liquid Layers
 Check out this picture from your
book. Which layer has the
highest density?
 Which layer has the lowest
density?
 Imagine that the liquids have the
following densities:
10g/cm3
6g/cm3
3g/cm3
5g/cm3
 Which number would go with
which layer?
Liquid Layers
 Check out this picture from your
book. Which layer has the
highest density?
 Which layer has the lowest
density?
 Imagine that the liquids have the
following densities:
10g/cm3
6g/cm3
3g/cm3
5g/cm3
 Which number would go with
which layer?
3g/cm3
5g/cm3
6g/cm3
10g/cm3
Liquid Layers
 Which liquid has the
highest density?
 Which liquid has the
lowest density?
 Which liquid has the
middle density?
Liquid Layer
 Which liquid has the
highest density?
Golden syrup
 Which liquid has the
lowest density?
oil
 Which liquid has the
middle density?
water
Liquid Layers – Try on your own!
 Imagine that the
liquids on the right
have the following
densities:
15g/cm3
3g/cm3
7g/cm3
10g/cm3
9g/cm3
12g/cm3
 Match the colors to
the correct densities.
3g/cm3
7g/cm3
9g/cm3
10g/cm3
12g/cm3
15g/cm3
Sink or Float
• Ice floats in
water because
the density of ice
is less than the
density of water.
• Aluminum sinks
because its
density is
greater than the
density of water.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
45
Liquids: Corn syrup is most dense, the water, then oil is least dense.
The Nut sinks to the bottom. It is the most dense material in the cup.
The grape is more dense than water and oil, but less dense than corn syrup.
The lego is more dense than oil, but less dense than water.
The styrafoam is the least dense material in the cup.
Video: ZOOM - Making Eggs Float
Don’t be dense!
Science will save the galaxy!