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Diffusion

Gas Pressure

Gases:

Shape and Volume of Gases

Gases have no definite shape

Gases take the shape of their container

Gases have no definite volume

Gases fill the entire space available in the container

They don’t have a fixed shape or volume, instead, it fills the space it is in.

But if you make a room full of gas smaller, the gas volume won’t change, it’s just compressed together (change in shape). But if the room is too compressed, it causes pressure.

Collision of gas in a wall of container cause pressure.

Like a balloon full of gas, it have pressure because the gas are constantly colliding into the wall.

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In this 3 box, the left sided one is having the most pressure.

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When the gas are colliding, the container might break as there is too much pressure.

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Keywords:

Atmospheric Pressure: The force exerted by the weight of the atmosphere on a surface, measured as the pressure per unit area.

Collide: To come into forceful contact with something, often resulting in a change of motion or energy.

Temperature: A measure of the average kinetic energy of particles in a substance, indicating how hot or cold it is.

Fluid: A substance that can flow and take the shape of its container, including liquids and gases.

You’re surrounded by a fluid called gas.

Liquids and gases are fluids

No fixed shape

Particles in a fluid exert pressure on a surface.

Example of liquid pressure:

When you go deeper into a swimming pool, the pressure is higher as there are more water/fluid above you.

Example of gas pressure:

In a airplane, high above ground, the pressure in lower, as there is less gas/fluid above you. The pressure here is atmospheric pressure.

So we can see:

The higher you are, the less pressure there is.

The lower you are, the more pressure there is.

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The reason there is pressure is because particles of a fluid are constantly in a motion. They are always moving, all the time.

So when they move inside a container, like a balloon. It exerts a force on the suface when colliding, this is called gas pressure.

So we can see, the gas pressure is caused by colliding particles of fluid exerting a force onto the surface area.

Gas pressure is measured in psi, pressure square inch, or Nm squared, Newton per squared meter.

But we will only focus on Nm squared

Formula: = force (N)/ area (meter squared)

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Gas pressure is affected by 3 factors:

Surface area - how big the container’s surface area is.

Quantity - amount of particles

Temperature - how much energy (kinetic)

Reason:

Surface Area:

Bigger area → gas spreads out more → less pressure.

Smaller area → gas has less space to hit → more pressure.

Quantity of Gas Particles:

More particles → more collisions with walls → higher pressure.

Fewer particles → fewer collisions → lower pressure.

Temperature:

Hotter gas → particles move faster → hit walls harder → higher pressure.

Colder gas → particles move slower → hit walls less hard → lower pressure.

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