thermodynamics - properties of substances

pure substance

has a fixed chemichal composition but may consist of more than one phase

solids molecular order

long range

liquids molecular order

medium or short range

gas molecular order

no real molecular order

compressed/subcooled liquid 

a liquid not about to vaporise if energy is added

saturated liquid

a liquid that will vaporise if any more energy is added to it

saturated vapour 

a vapour that will condense if any energy is taken away from it

superheated vapour

a vbapour not about to condense if energy is taken away from it

saturated mixture

a mixture of saturated vapour and saturated liquid in equilibrium

saturation temperature - notation and meaning

Tsat, the temperature at which vaporisation/condensation occurs at a specific pressure

saturation pressure- notation and explanation

Psat, the pressure at which vaporisation/condensation occurs at a specific temperature

3 factors for critical point

temperature,pressure,volume

critical point

liquid and vapour states indistinguishable from eachother

saturation curve

made by joining all the saturated liquid points and all the saturated vapour points, shows phase information

quality factor/dryness fraction word formula

mass of vapour/total mass of mixture

g phase

vapour phasef

f phase

liquid phase

i phase

solid phasefor

formula to calculate average properties of a mixture

yav = yf +x(yg-yf)

how to approximate subcooled liquids properties

approximate to the saturated liquid value at the specified temperature

calculating properties in superheated vapours

need both P and T , at extremem temperatures , the vapour behaves ideally