Particle model and pressure Flashcards
Describe the motion of molecules in a gas .
They are in constant random motion
What factor affects the average kinetic energy of the gas molecules ?
Temperature
> the higher the temperature the higher the average kinetic energy of the gas molecules
What affect does increasing temperature have on the pressure of a gas when held at constant volume ?
Pressure of gas will increase as the temperature increases
Why does pressure increase as temperature increases at constant volume ?
> kinetic energy of molecules increases
collisions between molecules becomes more frequent
greater rate of change of momentum
greater force and therefore pressure
If gas A is at low pressure and gas B is at high pressure , what can be said about the rate of collisions in each gas ?
> there are more collision per second in gas B than in gas A
> the rate of collisions is higher in gas B
Describe the force that the pressure of the gas exerts on the walls of the container ?
> the net force acts at right angles to the containers surface
the force increases as the pressure increases
Explain how increasing the volume of a gas results in a decrease of pressure ?
> molecules become more spread out and so time between collisions increases
this reduces the rate of collisions
rate of change of momentum decreases and so force exerted on container decreases resulting in a lower pressure
What can be said about the product of pressure and volume for a fixed mass of gas at constant pressure ( higher )
It’s constant
Pv= constant
What is the unit used for pressure ?
Pascal (Pa)
What increases when you do work on a gas ?
> the internal energy of the gas
> this can lead to an increase in temperature
Why does the temperature of air inside a bike pump increase when it’s pumped ?
> work is done on a gas when it’s compressed
doing work on a gas increases it’s internal energy so also increases the average kinetic energy of the gas molecules
temperature increases with an increase of average kinetic energy
