1. DENSITY
Mark Place,

2. DENSITY: The mass of a substance per unit of volume
DEFNITION
DENSITY: The mass of a substance per unit of volume
In simple terms…How much “stuff” is in a certain amount of space
Weight/amt of space taken up

3. Only way to change density is by changing the temperature or pressure

4. Opposite is true for cooling-> atoms contract
Heating an object causes the density to decrease --atoms become less tightly packed
Opposite is true for cooling-> atoms contract
Density

5. Density
density
temperature

6. Pressure
As pressure increases, the volume decreases causing higher density
As pressure decreases, volume increases causing lower density

8. SUMMARY
INCREASE TEMPERATURE, DECREASE DENSITY
DECREASE TEMPERATURE, INCREASE DENSITY
INCREASE PRESSURE, INCREASE DENSITY
DECREASE PRESSURE, DECREASE DENSITY

9. Water is the standard used to compare the density of objects

10. The density of water when it is most dense is: Density of water:
1.00 g/mL

11. 4 expands Density of water: Water is most dense at _______°C.
This is because water _______________ above
and below this temperature
expands
4°C

12. THE DENSITY EXCEPTION
Usually, solids are the most dense and gases are the least dense (think of Earth layers)
When water freezes into ice, the atoms expand become less packed
As a result, ice is less dense than water

13. THIS IS WHY ICE CUBES FLOAT IN WATER!

14. Any material with a density less than water will
Density of water:
Float or Sink
Any material with a density
less than water will
Any material with a density
greater than water will
FLOAT
SINK

15. DENSITY FORMULA
On the front page of the ESRT (Earth Science Reference Tables)
Density= mass/volume
Use a scale for mass
V= l*w*h for regular solids
Use cylinder and displacement method for irregular solids
Units:
g/cm3 for reg. solids; g/mL for irreg. objects

16. If substance is broken or more is added to it, nothing happens to the density (the atoms are still packed the same)
Density

17. Example 1: the density of a gallon of water is 1. 0 g/mL
Example 1: the density of a gallon of water is 1.0 g/mL. the density of a glass of water is also 1.0 g/mL
Example 2: a wood block cut in half has the same density as the original wooden block

18. Phases of Matter & Density- REVIEW
During which phase of matter (solid,
liquid, or gas) are most materials:
most dense?
least dense?
solid
gas

19. Sample Problems density = mass / volume = 240g / 12cm³ page 7
A rock has a mass of 240g and a
volume of 12cm³.
Showing all formulas and calculations,
determine the density of the rock.
Sample Problems
density = mass / volume
= 240g / 12cm³
page 7
= 20.0 g/cm³

20. Sample Problems density = mass / volume = 120g / 40cm³ page 7
The box below has a mass of 120g.
Showing all formulas and calculations,
determine the density of the box.
volume = L x W x H
Sample Problems
2.0 cm
= 2.0cm x 2.0cm x 10.0cm
10.0 cm
2.0 cm
= 40.0 cm³
density = mass / volume
= 120g / 40cm³
page 7
= 3.0 g/cm³

21. D = m ÷ v = 25g ÷ 50mL = 0.5 g/mL Density of water example:
If an object has a mass of 25g and a volume of 50mL, will it sink or float in liquid water?
D = m ÷ v
= 25g ÷ 50mL
= 0.5 g/mL
it will FLOAT

22. Video
Watch the following video. While you’re watching the video, write down at least 3 things in your notes that you find important, interesting, or helpful in remembering the concepts presented.