Gas Pressure & Temperature

PhysicsAQAGCSEUnit: Particle Model
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The basics

The Invisible Bombardment

📖 The Invisible Bombardment

Right now, trillions of air particles are smashing into your skin at around 500 m/s. You don't feel individual impacts because they're tiny, but together they create atmospheric pressure — about 100,000 Newtons pressing on every square metre of your body! Heat a gas and particles move faster, hitting container walls harder and more often. In a sealed container, pressure SKYROCKETS. That's why aerosol cans warn "Do not expose to heat" — they can literally explode!
Pressure Equation
p = F / A
Pressure (Pa) = Force (N) ÷ Area (m²)
Spotlight
The Particle Explanation of Gas Pressure

Gas pressure arises from the constant, random bombardment of container walls by gas particles:

Exam tip

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🧠 Memory Aid

Celsius to Kelvin: Add 273. Remember with: "Kelvin is Celsius + 273 — K is above 0, C starts at −273." Or simply: K = C + 273.

Gas pressure particle explanation — the 3-step answer:

  1. Particles move faster (higher kinetic energy)
  2. More frequent collisions with walls
  3. Greater force per collision → higher pressure

Pressure in liquids: "Deeper = Heavier burden above = Higher pressure." The diver analogy: the deeper you swim, the more water is pressing down on you from above.

Absolute zero: −273°C. Think "−273 is the floor — you can't go lower." Like the lowest floor of a building. Everything above is a positive Kelvin value.

Now try it yourself

Quiz · Question 1 of 19

A sealed gas container is heated. What happens to the pressure of the gas inside?

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