Week 2 lecture 2 Flashcards
substance composed of a single chemical species, which may exist in more than one phase
pure substance
molecules are arranged in a 3d pattern (lattice) that is repeated throughout
solid
molecules are no longer at fixed positions relative to each other and they can rotate and translate fully
liquid
the molecules are far apart from each other, and a molecular order is non-existent
gas
a liquid which is not about to vapourise
compressed liquid
liquid that is about to vapourise
saturated liquid
vapour that is not about to condense
superheated vapour
at a given pressure, the temperature at which which a pure substance changes phase
saturation temperature (T sat)
at a given temperature, the pressure at which a pure substance changes phase
saturation pressure (P sat)
Ideal gas equation
PV = nRT
Gibbs Phase Rule equation
number of degrees of freedom = number of chemical species - number of phases + 2
temperature and pressure at which the three phases (gas, liquid and solid) of that substance coexist in thermodynamic equilibrium
triple point
end point of phase equilibrium
critical point
for a single molecular species system as the highest temperature and pressure (Tc, Pc) at which liquid and vapour phases can exist in equilibrium
critical point
condition at which the properties of the gas phase (vapour phase) and liquid phase in equilibrium become identical
critical point
deviation of a real gas from ideal gas behaviour
compressibility factor (Z)
the ____ the deviation from the ideal gas law, the closer to Z is to 1
lower
the lower the deviation from the ideal gas law, the ______to Z is to 1
closer
equation for reduced temperature
reduced temperature = temperature/critical temperature
equation for reduced pressure
reduced pressure = pressure/critical pressure
reduced properties are _______
dimensionless
generalised gas equation with compressibility factor
PV = ZnRT
critical compressibility factor equation
Zc = reduced pressure*reduced volume / R * reduced temperature
