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Density and states of matter
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The particle model explains solids, liquids and gases, and why they have different densities.
Density
density = mass ÷ volume, ρ = m ÷ V.
Units: kg/m3 or g/cm3. 1 g/cm3 = 1000 kg/m3.
Units: kg/m3 or g/cm3. 1 g/cm3 = 1000 kg/m3.
The particle model
Measuring density
For a regular solid: measure the sides with a ruler and calculate the volume.
For an irregular solid: lower it into a displacement (eureka) can and measure the volume of water pushed out.
For a liquid: measure the mass of a known volume using a measuring cylinder and balance.
For an irregular solid: lower it into a displacement (eureka) can and measure the volume of water pushed out.
For a liquid: measure the mass of a known volume using a measuring cylinder and balance.
A block has mass 540 g and volume 200 cm3. Find its density.
- ρ = m ÷ V
- 540 ÷ 200
Answer: 2.7 g/cm3
ρ = m ÷ V. Gases are much less dense because their particles are far apart. Use a displacement can for irregular objects.
The interactive lesson includes the diagrams for this topic.
Check you have got it
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