Condensation of a supersaturated vapor. II. The homogeneous nucleation of the n-alkyl benzenes

Abstract

The design of an improved version of the upward thermal diffusion cloud chamber is described. Such a chamber was constructed and used to measure the supersaturations required to observe a rate of homogeneous nucleation of 2-3 drops cm-3 ·sec-1 Measurements were made on benzene, toluene, orrho -xylene, and n -butylbenzene over as much as a 150'C range of temperatures. The results obtained are compared to the predictions of the classical theory of homogeneous nucleation (Volmer-Becker-Doring-Zeldovich) and of the Lothe-Pound theory. The classical theory is found to be in excellent agreement with the experimental results. an improved version of the diffusion cloud chamber Katz 18 (in the first paper of this series, which we hereafter refer to as I) found that, for n-hexane, n-heptane, n-octane, and n-nonane over the 100 qc range of temperatures studied, the measured supersaturations which caused homogeneous nucleation were very accurately predicted by the classical theory.At about the same time Wegener 19 began studies of homogeneous nucleation in a supersonic nozzle. He and his co-workers obtained good agreement with the classical theory for water 20 and for ethanol. 21 In view of this agreement of results with each other and with theory by various methods and by different workers, one might 448

On the barrier-limited condensation of water on hexadecane

“…In [8] a good agreement is found by the diffusion chamber method with the data of Volmer and Flood for water, ethanol and methanol and results coinciding with the classical theory are reported for the non-polar hexane. The classical theory is also confirmed by the data for heptane, octane and nonane in [9] ; for benzene, toluene, orthoxylene, n-butylbenzene in [10]; for carbon tetrachloride, chloroform, freon 11 and 1,1,2,2,-tetrachloroether in [11]; and for o-xylene and m-xylene in [12].…”

“…According to formulae (1) and (5) ln S~(barrierless) _ fmax (al) In Sc (barrier, Z = 1) f~z=l)(al) (10) With fmax(al) = --37.62 and f(al) = -28.9, which we assume to correspond to the outset of barrierless phase formation, we obtain In S c (Z = 1) = 0.194. In other words, if the sensitivity of the method of detecting condensation is increased sufficiently, dependence of the impulse intensity I on supersaturation in S of the kind shown in figure 4 should be expected.…”

“…There, the increase in I with the supersaturation is hindered by W II -W I > 0. The abscissa of point "b" corresponds to the outset of barrierless phase formation, and point "a" at Z = 1 is shifted to the left: to In Sc = 0.19, according to equation (10).…”

Condensation of a supersaturated vapor. XII. The homogeneous nucleation of the n-alkanes

“…Details of its design and operation have been published 18,19 so only a brief description of the chamber will be given here. The chamber consists of two circular copper plates separated by a 290 mm i.d.…”

Aerosole

“…Die tatsachlichen numerischen Werte der experimentellen Keimbildungsraten und deren Temperaturgang weichen jedoch betrachtlich von der klassischen Keimbildungstheorie abo Ahnliche Verhaltnisse wurden auch fur eine Reihe anderer Substanzen festgestellt, wobei insbesondere bei den niedrigeren Alkoholen starke Abweichungen von Theorie und Experiment auftreten. Mit Hilfe von Diffusionskammern wurde fur eine Anzahl verschiedener Substanzen die kritische Ubersattigung bei homogener Keimbildung bestimmt, wobei im allgemeinen annahernde Ubereinstimmung mit der klassischen Keimbildungstheorie gefunden wurde [36,37). Messungen von kritischen Ubersattigungen liefern jedoch einen wesentlich unempfindlicheren Test der Keimbildungstheorie als Messungen von homogenen Keimbildungsraten.…”