SATURATED VAPOR-PRESSURE AND INTERNAL-PRESSURE FOR LIQUIDS

By using statistical thermodynamics, a relation between saturated vapor pressure p(s) and internal pressure p(i) of liquids has been derived, p(s) = p(i)/sigma exp (- p(i)V(m)/nRT) where sigma is a factor which is dependent on density or molar volume V(m) of liquids as follows, ln sigma = 1/2 ln (V(m)2/V(m)2 - AV(m) + B) + A/square-root 4B - A2 tg-1(2V(m) - A/square-root 4B - A2) - 6.60 and n, A, B are characteristic constants. The results of testing for C6H6, CCl4, cy-C6H12, C(CH3)4, n-C6H14 and (CH3)2CO indicate that this relation is valid in wide temperature range.