thermal physics

• Boyle's law states that at constant temperature the pressure (p) and volume (V) of gas are inversely proportional

  pV=constant
• Charles' law states that at constant pressure the absolute temperature (T) and volume (V) of a gas are directly proportional. temperature must be in kelvin

  V/T = constant
• the pressure law states that at a constant volume the absolute temperature (T) and pressure (p) of a gas are directly proportional. temperature must be in kelvin

  p/T = constant
• Brownian motion is evidence for the existence of atoms
• the Avogadro constant (Na) is defined as the number of atoms in exactly 12g of the isotope carbon-12
• the molar mass (M) of a substance is the mass that one mole of the substance would have, in grams - which is equal to the substance's relative atomic/molecular mass

  The total mass of a substance (ms) is therefore given by:

  Ms=nM
• if a substance consists of molecules, the number of molecules (N) is given by:

  N=nNa
• an ideal gas is an imaginary gas which obeys Boyle's law perfectly
• unlike the ideal gas laws, the kinetic theory model arises from theory
• several assumptions made on the kinetic theory model:

  there are no forces between molecules except during collisions

  the collisions the gas molecules undergo are perfectly elastic

  the volume of molecules is negligible compared to the volume of the container

  the time of collisions is negligible compared to the duration between impacts
• internal energy is the sum of the randomly distributed kinetic energies and potential energies of the particles in a body
• the temperature of a body is a measure of the random distribution of the kinetic energies of the vibrating particles of a body
• during a change of state, the potential energies of the particle ensemble are changing but not the kinetic energies
• the internal energy of a system is increased when energy is transferred to it by heating or when (mechanical) work is done on it (and vice versa)
• absolute temperature is measured in kelvin
• the specific heat capacity (c) of a substance is defined as the amount of energy needed to raise the temperature of 1kg of the substance by 1K (or 1°C)
• specific = per unit mass
• as the substance changes temperature, the kinetic energies of the particles are changing
• the specific latent heat (l) of a substance is defined as the amount of energy needed to change the state of 1kg of the substance without a change in temperature
• specific latent heat of fusion = solid changes to liquid
• specific latent heat of vaporisation = liquid changes to gas