DENSITY

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DENSITY
Let’s understand it once and for all!
TO CALCULATE
Mass
Density = -----------Volume
OR
m
D = ----v
THE TRIANGLE TRICK
m
D
v
On your paper, draw the triangle and write the
three formulas you can derive from this triangle.
UNITS

For mass, units may be grams, kilograms,
centigrams, etc.

For liquid volume, units may be liters,
milliliters, kiloliters, etc.

For solid volume, units may be cubic
centimeters, cubic meters, etc.
DERIVED UNITS

The unit for density is a derived unit because it
is a combination of two other units.

Just as you divide the numbers to solve the
problem, you also divide the units.

Ex. If mass is in g, and volume is in cm3,
then the units for density will be:
g
----cm3
QUESTION

What would be some possible units for the
density of a liquid?
LET’S DO SOME WORK

What is the density of 10 mL of a
substance with a mass of 8 g?
m
D = ---v
8g
D = ------10 mL
g
D = 0.8 ---mL
MORE WORK TO DO

Now, we will figure the density of half the
amount of the same substance.
– What is the mass? 4 g
– What is the volume? 5 mL
g
– -----------What is the density? 0.8 ----mL
SAME AS BEFORE!!! WHY???
DENSITY IS A PHYSICAL
PROPERTY

Density does NOT depend on a substance’s shape
or size.

Density for a substance does NOT change whether
the substance is in a big amount or a small
amount.

Density depends on a substance’s chemical
composition, pressure, and temperature. If any of
these things change, the density may change.
TAKE WATER FOR EXAMPLE
The chemical formula for water is H2O.
g
 Water has a density of 1.0 --- .
mL
 A single drop of water has that density.


A bathtub full of water also has that density.
The mass increased, but so did the volume.
The ratio of the two after dividing is the SAME.
WILL IT FLOAT?

If a substance has a density that is less
than the density of water, it will float.

If it has a density that is more than the
density of water, it will sink (it is heavier).

Will the substance from our earlier work
float in water?
MORE WORK
Calculate the volume of an object if you know that
the object has a mass of 14 grams and the density
is 12 g/mL.
Calculate the mass of an object if you know that the
object has a density of 13 g/mL and the volume is
5 mL.
Calculate the density of a liquid in a beaker. The
beaker has a mass of 15 grams when empty. The
beaker plus an unknown liquid has a mass of 43
grams. What is the density of the liquid if its
volume is 10 mL?
Identify the materials in the density column to the right
by using the data table to help you.
40 mL
Liquid
Material
Material A
Milk
30 mL
Material B
20 mL
Fingernail
Material C Polish Remover
10 mL
Density (g/ml)
1.02
0.78
Olive Oil
0.92
Citric Acid
1.66
Material D
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