Density 2
Science Practicals: GCSE, topic 3.1.7
Density and the Particle Model
Differences in the density of solids, liquids and gases can be explained using the particle model of matter.
Solids
- Solids are the most dense state of matter.
- The particles are packed tightly together.
Liquids
- Liquids are less dense than solids but more dense than gases.
- The particles in liquids can move around each other.
Gases
- Gases are the least dense state of matter.
- The particles are free to move with negligible (tiny) forces between particles.
Calculating Density
To find out the density (density=mass/volume) of an object, we measure its mass and volume. We can measure the mass of an object using a balance (scales). We can calculate the density of:
Liquids
- For measuring the density of liquids, place a measuring cylinder on a balance and set the reading to zero.
- Pour the liquid into the cylinder and write down its mass and volume. Then calculate the density.
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Irregularly shaped solids
- For solids, we can use the Law of Displacement to estimate its volume.
- This is done using a displacement can, or a graduated measuring cylinder.
- The volume of displaced water is measured, and this is the volume of the object.
Test yourself on Density 2
Density
What is the law of displacement?
Which two quantities do you need to calculate density?