1. Unit 1 Mix and Flow of Matter
Topic 5
Density
Remember to name and date your notes!

2. Density
Density is the “crowdedness” of the particles that make up matter.
Each substance has it’s own unique density based on how close together the particles are.

3. The particles of a liquid/gas move apart easily, allowing a more dense, solid object to pass through.
The attractive forces between the particles in a liquid/gas are not strong enough to prevent a solid object from pushing them apart.

4. In general, gases are less dense than liquids, and liquids are less dense than solids.
Particles in a solid cannot easily be pushed apart – the attractive forces between particles are very strong.

5. WHAT ABOUT THE DENSITY OF WATER AND ICE?
Ice is less dense than water – air bubbles are trapped in the ice.

6. Density (D) = Mass(m) / Volume (V)
DENSITY FORMULA
Density (D) = Mass(m) / Volume (V)
D = m / V

7. DENSITY FORMULA
Mass is the amount of matter in a substance (we could use a balance to determine this in grams or kilograms)
Mass and Weight are not the same.

8. Weight is the force of gravity exerted on an object.

9. Volume is the amount of space occupied by a substance
Volume is the amount of space occupied by a substance. We can calculate using:
V = l x w x h
Or, we can use the displacement method for irregular shaped objects. (see page 53)

10. The density of solids is given in g/cm3
The density of a liquid is given in g/L or g/mL
Eg. The density of an object, having a mass of 15g and a volume of 3cm3 is:
D = m / V
D = 15g / 3cm3
D = 5g/cm3

11. The average density of salt water is 1.03 g/mL
The average density of fresh water is 1.0 g/mL
Anything with a density below 1.0 g/mL will float. Anything with a density above 1.0 g/mL will sink.

12. SINK OR FLOAT IN FRESH WATER?
MERCURY g/mL
CORK g/cm3
SUGAR g/cm3
OAK g/cm3
ALUMINUM g/cm3
SINK
FLOAT
SINK
FLOAT
SINK