Particle theory says that gases consist of very small particles which are constantly moving in completely random directions.
Brownian motion supports the particle theory because large, heavy particles can be moved with Brownian motion with smaller, lighter particles travelling at a high speed. This is way particles appear to be moving around randomly when you observe them in a lab.
Gases have a random motion, so when they collide with something they exert a force on it, and their momentum and direction change.
In a sealed container gas particles smash particles against the container walls- this creates an outward pressure. The pressure depends on how fast the particles are going and how often they hit the walls (average speed)
Absolute Zero
The coldest that anything can get is -273℃ - this temperature is called/ known as the absolute zero. At the absolute zero, atoms have little kinetic energy as it's possible to get.
Kelvin scale
unit: K
begins at the absolute zero (-273℃) and so there are no minus numbers
temperature in degrees Celsius = temperature in Kelvin - 273
temperature in Kelvin = temperature in degrees Celsius + 273
The temperature of a gas (in Kelvin) is proportional to the average kinetic energy of its particles
As the kelvin increases, energy increases. As the energy of something increases, its particles will move faster and with more force. This means that more force is exerted over a fixed area increasing the pressure.
So if a gas has its kelvin increased, it will exert more force on its container, and then pressure goes up.
pressure/ temperature (in K) = constant
p/T = constant
or: p1/T1 = p2/T2
pressure x volume = constant
pV = constant
p1V1 = p2V2
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