Properties of Pure Substances Flashcards
Pure Substance
- Fixed chemical composition
- Can exist in more than one phase
- Homogeneous (can be mixture, but not oil or water)
Compressed/Subcooled Liquid Region
A liquid that is not about to vaporised
Sensible energy
The energy change can be measured by some parameter, e.g. temperature change
Saturated liquid
At 100 C and 1 atm liquid water is termed a saturated liquid
Superheated vapour
- Any addition of heat causes an increase in sensible energy
- Any removal of heat will cause a decrease in the sensible energy
Saturated Temperature
At a given pressure, the temperature at which a pure substance changes phase
Saturated pressure
At a given temperature, the pressure at which a pure substance changes phase
Latent heat
Amount of heat absorbed or released during a phase change
Latent heat of fusion
Amount of energy absorbed during melting
Latent heat of vaporisation
Amount of energy absorbed during vaporisation
Equal to energy released during condensation
Critical point
The point at which the saturated liquid and saturated vapour states are identical
Quality/Dryness fraction
Ratio of mass of vapour to total mass of mixture
Specific volume
Total volume of system per total system mass
Enthalpy (H)
- Combination of properties U and pV
- Amount of energy required to vaporise a unit mass of a substance (from quality 0 to quality 1)
Equation of state
Any equation that relates the pressure, temperature and specific volume of a substance
