Density
a physical property of matter
Property = a characteristic that gives
a substance identity
Properties of Vinegar:
- clear liquid
- strong odor
- reacts with baking soda
- acidic
Physical Properties
can be observed without changing the
composition of the substance
Examples;
-Color
-Buoyancy
-Texture
-Shape
-Hardness
-Viscosity
-Miscibility
-Density
Brick is more dense
than Styrofoam
because there is
more mass
packed into the
same volume
(more molecules or
atoms in the same
space.)
DENSITY
Styrofoam
Brick
Density
Density can be defined as
“unit mass per unit volume”
Density = Mass / Volume
D=m/v
Example: Density
Density is a property of matter. If you measure
the mass (g) and the volume (mL) of an object,
you can calculate it’s density using the formula:
D = m/v
Density = mass/volume
So, the units of
density must be….
g/mL
The Units for density come
from this formula…
• Why is density measured in g/mL?
(aka “grams per milliliter”)
(not “gee slash em-ell”)
Because the formula for density is
m
mass
(in grams)
g
D = ----- = ------------  --------------  ---v
volume
(in milliliters)
mL
Measurement
Metric System
Quantity
Unit
Unit Symbol
Length
meter
m
Mass
gram
g
Volume
liter
L
Time
second
s
Temperature
Kelvin or
degree celsius
K
or
oC
Volume is
special
because:
• Volume can be
measured in
liters (L),
milliliters (mL), etc. s
or…
OR…
• Volume can be
measured in
cubic meters (m3)
centimeters (cm3),
…..etc.
Remember;
1 cm3 = 1 mL
Remember this geometry?
• Volume of a cube is ….
lxwxh
i.e.
4cm x 5cm x 2cm = 40 cm3
•Volume of a cylinder is ….

2
r h
i.e.  x (5cm)2 x 10cm = 250 cm3
Determining the Volume of an
Irregularly Shaped Solid
22 mL
32 mL
Units of Density:
1 cm3 = 1 mL
– Mass is measured in g.
– Volume is measured in mL or cm3.
– Density is mass / volume,
(g) / (mL)
(g) / (cm3) ,so..
density is measured in:
g/mL
or
g/cm3
DENSITY - an important
and useful physical property
Density 
mass (g)
volume (cm3)
Mercury
Platinum
Aluminum
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3
Atoms of some elements are more dense
than others.
Density of Gold:
19.30 g/mL
Silver:
10.50 g/mL
Aluminum:
2.70 g/mL
Substance
• Air
• Wood (Oak)
• Steel
•Water
Density (g/mL)
0.0013 g/mL
0.80 g/mL
7.80 g/mL
1.00 g/mL
Sample Problem
• What is the density of 5.0 g of tin
that has a volume of 1.2 mL?
D =?
m = 5.0 g
v = 1.2 mL
D= m / v
= 4.2 g/mL
Steps for Solving Problems
1. Write the shopping list:
•
the unknown variable. (what’s the question asking for?)
•
all of the known variables.
2. Write the formula you will be using.
3. Calculate the final answer and include the units.
Sample Problem
• What is the density of 45.0 g of a
liquid that has a volume of 62.5 mL?
D =?
m = 45.0 g
v = 62.5 mL
D= m / v
=
g/mL
Variations of the Density Formula:
D = m/v
m
D
v
v = m/D
m=v•D
Sample Problem
What is the volume of 21.0 g of
tin? (Density of Tin = 4.2 g/mL)
v=?
v=m/D
D = 4.2 g/mL
v = 5 mL
m = 21.0 g
Sample Problem
What is the mass of 20 cm3 of
tin? (Density of Tin = 4.2 g/mL)
m=?
D = 4.2 g/mL
= 4.2 g/cm3
v = 20 cm3
= 20 mL
m=vD
m = 84 g
Review:
3 methods of measuring volume:
•
directly using glassware
•w•h)
•
geometry (e.g. l
•
water displacement (vf – vi)
Variations of the Density Formula:
D = m/v
v = m/D
m=v•D
1. Write the unknown variable.
2.
Write all the known variables.
3.
Convert all variables to similar units.
4.
Write formula you will be using.
5.
Calculate: “Plug and Chug”
6.
Circle your final answer with correct units.