PROPERTIES OF PURE SUBSTANCES

Pure substance

Vapour-Liquid-Solid Phase Equilibrium

Equation of State

Chemical analysis;the ratio of hydrogen and oxygen is 2:1

Gases can be pure when there is no change in phase

Has more than one phase but with same chemical composition

Fixed chemical composition Ex(water)

liquid air and gaseous air is not pure substance

the pressure remains constant when heat is transferred to water,but specific volume and temperature increase

working fluid(solid,liquid and gas)

Saturation:pressure and temperature are not independent properties

Temperature

Pressure

the temperature at which vaporization happens

the pressure effected by temperature is called "saturation pressure"

Saturation liquid

Copressed liquid

pressure is greater than the saturation pressure for given temperature

subcooled liquid

temerature is lower than saturation temperature of given pressure

Quality X

if liquid and vapor exisit simunatsously is defined by the ratio of mass of vapour to the total mass

Superheated vapour

when the vapour temperature greater than the saturation temperature

any equations that relates to pressure ,temperature and specific volume

Ideal gas equation PV=RT

at higher densities ,the ideal gas law cannot be applied

At very low density all gases and vapours become ideal gases