A new equation for calculating the heat of vaporization was derived For alkanes

monoolefines

ethers (nonring)

nitrils

ketones (ring and nonring)

organic acids and organic anhydrides

K2 = 4.358 For alkylbenzenes and polyphenyls(biphenyls

terphenyls) K2 = 4. 435 For cyclitols

alcohols(except diols

aromatic alcohols)

K2 = 4.581 For all other compounds and gases

Where Tt - normal boiling point

K Tc - -critical temperature

K Pc - critical pressure

atm. This equation applies to nonpolar and polar liquids at their normal boiling points and gives average and maximum errors of 1.65% and 12. 2% respectively for 157 compounds.