more changes of state Flashcards
What is the temp of gas related to?
Average kinetic energy of molecule
What does changing the temp of a gas at a constant volume do?
Changes pressure exerted by the gas
Explain how motion of molecules in a gas is related to both its temp and pressure
When gas particles collide they exert a force. In a sealed container the outward gas pressure is the total force exerted by all particles in the gas in a unit area of container walls.
Fast particles and more frequent collisions both lead to increase in net force, and so gas pressure.
If temp constant, increasing volume of gas means particles spread out and hit walls less often. Pressure decrease
Pressure and volume inversely proportional- when volume goes up, pressure goes down
For gas of fixed mass at constant temp:
pV= constant
What is the energy needed for a substance to change state called?
Latent heat
What is the specific latent heat of a substance?
The amount of energy required to change the state of one kilogram of the substance with no change in temperature
Equation for specific latent heat
Energy for a change of state= mass x specific latent heat
E= m L
What is specific latent heat measured in?
J/kg
What is specific latent heat of fusion?
Change of state from solid to liquid
What is specific latent heat of vaporisation?
Change of state from liquid to vapour
Pressure in gases
Gas can be compressed or expanded by pressure change. Pressure produces net force at right angles to wall of container.
Also force outside container
Increasing the pressure of a gas
Doing work on a. gas increases internal energy of gas and can cause increase in temp if gas
How does doing work on an enclosed gas lead to an increase in temp of gas
With a bicycle pump, gas applies pressure to plumber if pump and exerts force on it. Work has been
done against force to push down plunger
Transfer energy into kinetic energy stores of gas particles, increasing temp. If pump connected to tyre should get warmer