Which has more mass?
A) 1 kilogram of feathers
B) 1 kilogram of bricks
They are the same!
1 kg = 1 kg
Which takes up more space?
A) 1 kilogram of feathers
B) 1 kilogram of bricks
The Feathers
Measure matter by finding
the density!
Which has the greater density?
A) steel paper clip
B) steel bar
The density of steel is the
same! Size doesn’t matter!
Density of Steel
steel bar
Units for Density
Metric Units:
Solid: g/cm3
Liquid: g/mL
Density of water is
Memorize
This!
1g/mL
(at 4º C)
Which one floats? Why?
• Density of Water:
1.00 g/mL
• Density of Ice:
0.92 g/mL
Which of the following will float on water?
Why is it good to know the density?
Density
helps you
identify a
substance
All those less
than 1.0 g/mL
Predict the correct “floating order” of the substances as
they would appear in the “Density Column”.
Substance
Density
g/cm3
Copper
Corn oil
Corn syrup
8.8
0.925
1.38
Glycerin
1.26
Mercury
Plastic
Rubber
Tar
13.6
0.93
1.34
1.02
Water
Wood
1.00
0.7
Specific Gravity
Specific Gravity Density of Substance (g/cm3)
=
3
Density of Water (g/cm )
Specific gravity is the same as the density except:
There are no units! Why? Because they cancel!
Ex:
Density of water: 1 g/cm3
Specific Gravity of water: 1 (no units!)
What is the specific gravity?
It is the same as the density but it has no units!
Calculating Density
• Obtain mass using a balance.
• Obtain volume by any of these methods.
– Ruler: Volume = L x W x H
– Graduated cylinder
– Water displacement
m
“Magic Circles” 
d
v
d = m/v
m=dxv
v = m/d
1) Is the bar really gold or fool’s gold?
Find the density of the bar if the mass is
1891.4 g and the dimensions are 3.50
cm by 3.50 cm by 8.00 cm.
• Gold has a density of
19.3 g/cm3
V=LxWxH
D = M/V
1891.4 g / 98.0 cm3
= 19.3 g/cm3 Yes it’s gold!
What is the
Specific
Gravity?
m
d
v
2)
Is this liquid water, alcohol, or kerosene?
Find the density of the liquid if the mass
is 16.98 g?
Water 1.0 g/mL
Alcohol 0.79 g/mL
Kerosene 0.82 g/mL
• Read the volume 
D = M/V
16.98 g / 21.50 mL
= 0.7900 g/mL It is
alcohol!
What is the
Specific
Gravity?
m
d
v
3)
Is the “Silver Surfer” really made of
silver? We obtained a sample with a
mass of 262.5 g.
Platinum 21.5 g/cm3
Silver 10.5 g/cm3
Tin 7.3 g/cm3
Find the volume by water
displacement.
d = m/v
= 262.5 g / 25.0
cm3
m
d v
= 10.5 g/cm3 It is Silver!
4)
What is the volume in mL of this syrup if
it has a density of 0.630 g/mL and a
mass of 78.00 g?
v = m/d
= 78.00g ÷ 0.630
g/mL
= 124 mL
m
d
v
5)
What is the mass in grams of this lead
pipe if it has a density of 11.4 g/cm3 and
a volume of 55.0 cc?
m=dxv
= 11.4 g/cm3 x 55.0 cc
= 627 g
m
d
v