Year 9 · Science
Density and pressure worksheet for Year 9
For the solids, liquids and gases lesson, start with tasks 1 and 2. They compare the three states and explain gas compression. Tasks 3 to 6 add density and warming if you want to go further. You can type here, choose to save your work in this browser, or print it.
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TheLearnDenYear 9 · Science
TheLearnDenYear 9 · Science
Density and pressure worksheet
Part 1 · Particles and compression
Name (optional):
The air inside the balloon is a gas. Dots are not to scale.
1 Quick recap
For each state, give its shape, volume, particle arrangement and movement.
Use these words where they fit: fixed, container’s shape, fills the container, close, far apart, vibrate, move past one another, all directions.
Show a planning hint
Think about what stays fixed in each state, then describe particle arrangement and movement.
| State | Shape | Volume | Particle arrangement | Particle movement |
|---|---|---|---|---|
| Solid | Solid: Shape: | Volume: | Arrangement: | Movement: |
| Liquid | Liquid: Shape: | Volume: | Arrangement: | Movement: |
| Gas | Gas: Shape: | Volume: | Arrangement: | Movement: |
2 Same gas, less room
A closed syringe holds the same amount of gas. Its temperature stays the same as its volume decreases.
Show a planning hint
Keep the amount and temperature fixed in your explanation.
Do the particles get smaller, or do the gaps decrease? Explain.
With mass unchanged, what happens to density? Use mass divided by volume.
What happens to pressure? Explain using collisions with the container walls.
TheLearnDenYear 9 · Science
Density and pressure worksheet
Part 2 · Density and warming
Name (optional):
Show your working. Include the units in each density answer.
3 Calculate density
Sample A has mass 24 g and volume 8 cm³. Write the formula, show your working and find its density in g/cm³.
Show a planning hint
Use density = mass ÷ volume, and include g/cm³ in both answers.
Sample B has mass 30 g and volume 30 cm³. Calculate its density in g/cm³.
Which sample is denser? Explain using your two answers.
4 Pressure when a gas is warmed
Compare the same amount of gas before and after warming in a sealed, rigid container. The volume stays fixed.
Why does pressure rise? Explain particle speed, collisions with the walls and force per unit area. Keep particle size and count the same.
Does the density change? Explain using mass and volume.
Show a planning hint
Explain the collision mechanism step by step; distinguish movement, force on the wall and pressure.
TheLearnDenYear 9 · Science
Density and pressure worksheet
Part 3 · Check and compare
Name (optional):
Keep particle size and count the same in both models.
5 Check the model
Sam says, “When a gas is compressed, its particles get smaller.”
Correct Sam’s claim.
Show a planning hint
Your before and after sketches should have the same count and equal dot sizes.
Sketch before and after compression. Keep the count and dot size the same.
Before compression
Use equal-sized dots for the particles.
After compression
Keep count and dot size the same.
6 Compare two gas changes
Both cases start with the same amount of gas. In A, the gas is compressed to half its original volume at the same temperature. In B, it is warmed in a sealed, rigid container at a fixed volume. Particle size and count stay the same.
Show a planning hint
Compare a volume change at fixed temperature with a motion change at fixed volume.
| Condition or result | A: compressed | B: warmed |
|---|---|---|
| Density | Density in A: | Density in B: |
| Pressure | Pressure in A: | Pressure in B: |
Explain why the causes of the pressure changes differ.
Do not calculate a pressure ratio.
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