Some aspects of the estimation of n by vapor pressure osmometry



The constants a,b of the equation log n = ab log [lim (ΔR/c)] in benzene and chloroform were obtained at 25, 37, and 45°C for the Knauer vapor osmometer and compared with those published by Brzeziňski et al. for the Mechrolab 302. It was found that the constant b in the above solvents had identical values, depending on the temperature used. The value of a depends on the resistance of the thermistors. The procedure used for obtaining lim (ΔR/c) from the concentration dependence is discussed. Comparison of the limiting slope dependence and the gradient dependence reveals the error of the zero point, which cannot always be eliminated by employing a procedure by Glover.