Thermal Physics Flashcards
Define absolute zero
? The lowest temperature that is theoretically possible ( at this temperature particles would stop vibrating and exert zero pressure
Define Charles law
? Volume is directly proportional to temperature (K) at a constant pressure
V1/T1=V2/T2
Define Boyles law
? Pressure is inversely proportional to volume at a constant temperature. (Isothermal Change)
A gas at very high temperatures does not obey this law.
P1V1 = P2V2
Define Lussac’s Law
? Pressure is directly proportional to temperature (K) at a constant volume
P1/T1 =P2/T2
Define internal energy
? Is the sum of the randomly distributed kinetic energies and potential energies of the particles in a gas.
Properties of ideal gases
? Particles have no potential energy
- all collisions are elastic
- point masses
- no change of state
Define specific heat capacity
? the energy required to raise the temperature of 1kg of a given substance by 1 Kelvin
Equation to calculate S.H.C
Q = mc (change) T
Unit: J/kgK
Define specific latent heat
? The energy required to change the state of a 1kg of a substance without a change in temperature.
Equation for specific latent heat
E =mL
Units: J/kg
Conversion between Kelvin and Celsius
-273 Degrees = 0K
What in the kinetic theory
? The molecules of a gas are in a state of constant motion in which the speed and the direction of each molecule is completely random.
Assumption of the kinetic theory
- The molecules of a particular gas are identical and in random motion
- The collisions between the molecules and between the walls of the container are perfectly elastic
- The volume of a molecule is negligible, compared to the volume of the container
- There are no intermolecular attraction between the molecules
- The time taken for a collision between two molecules is negligible compared with the time taken for the collisions between a molecule and the wall
Steps to derive the equation
- Find an expression for the change in momentum when the ball collides
- Find an expression for the force (Δmv/t) from point 1 to point 2
- Find an expression for the pressure (F/A) due to this force
- Multiply by N molecules (total number in the container)
- Substitute Crms for Vx using the equation earlier
Equation for ideal gas
PV/T = k
pV =nRT / pV =NkT
