The sorption of carbon tetrachloride at low pressures by activated charcoals. Part III.— isosteres —discussion

Abstract

The essential ain of these measurments of the dependence of equilibrium pressure on temperature for charcoals with definite charges of carbon tetrachloride was the calculation of heats of sorption by the Clapeyron-Clausius equation. This was effected by plotting each isostere in the form of the logarithm of the pressure against the reciprocal of the absolute temperature, the slope of the resulting linear curve measuring the molecular heat of sorption. A few points regarding experimental detail will be briefly referred to. The number of pressure-temperature measurements made on each charged charcoal sample varied between 3 and 13. As each pressure measurement involved opening up the charcoal container to the pressure gauge and connecting tubes (of total volume about 330 c. C.), this space was, prior to turning the container tap, charged with carbon tetrachloride vapour from the supply bulb until its pressure was near to (although still below) the pressure which it was estimated the charged charcoal would exert at the temperature in question. In this way, loss of sorbate from the charcoal during the set of measurements, which might have proved appreciable without this precaution, was reduced to a quite negligible figure.