Particle motion In Gases Flashcards
A particle model…
Helps explain how temperature and pressure and volume and energy in kinetic stores are all related
The particles in a gas are…
Are constantly moving with random directions and speeds
If you increase the temperature of a gas
You transfer energy into the kinetic energy stores of its particles
The temperature of a gas is related to the
Average energy in the kinetic energy stores of the particles in a gas.
The higher the temperature
The higher the average energy
So as you increase the temperature of the gas
Average speed of its particles increases. This is because the energy in the particles kinetic energy stores is 1/2 MV squared-
As gas particles move about at high speeds
They bang into each other and whatever else happens to get in the way
When gases collide with something
They exert a force and so pressure on it
In a sealed container
The outward gas pressure is the total force exerted by all of the particles in the gas on a unit area of the container walls.
Faster particles and more frequent collisions both lead to an
Increase in net force and so gas pressure
Increasing the temperature will increase the speed
And so the pressure volume is kept constant
Alternatively, if temperature is constant
Increasing the volume of a gas means the particles get more spread out and hit the walls of the container less often. The gas pressure decreases.
Pressure and volume inversely portional when volume goes up
Pressure goes down
What is the formula for a glass of fixed mass at a constant temperature
PV equals constant (pressure in pascals (Pa)
V = volume (m3)
The pressure of a gas causes…
A net outwards force at right angles to the surface of its container
There is also a force in the
Outside of the outside of the container due to the pressure of the gas around it
If the container can easily change it size
Then any change in these pressures will cause the container to compress or expand, due to the overall force
If you transfer energy by applying a force
Then you do work
Doing work on a gas increases internal energy
Which can increase its temperature
You can do work in a gas
Mechanically (eg with a bike pump)
The gas applied pressure to the plunger of the pump
And exerts a force on it
Work has to be done against a force
To push down on something
This transfers energy to the
Kinetic energy of the gas particles increasing the temperature
