also estimate the thermodynamic quantities for the process HC1 (gas) + HC1 (ice) and find that AH0 = -21.68 kcal/mol, AGO = -7.88 kcal/mol, and Ai30 = -48.2 cal/(mol deg). These results are obtained using wellknown thermodynamic data for the process HC1 (gas) -t HC1 (water).20 The equilibrium constant, K = (concentration of HC1 in ice)/(activity of HC1 in water), is 6.39 X 10-6, 1.78 X 10+, and 2.14 X at temperatures of -4, -11, and -18", respectively.The mode of incorporation of chloride ion in ice and the path of diffusion is suggested by the large hexagonally shaped channels that appear in the ice structure. These channels define the C axis, and this is the direction of diffusion. It is proposed that diffusion proceeds through and dissolution occurs in these hexagonal channels. On the basis of the above model we may predict that diffusion perpendicular to the C axis should be much slower than diffusion along the C axis.The technique described in this paper should be applicable to solubility studies in other solids that have low melting points, as long as they can be prepared in the form of large single crystals. In cases where the solubility is appreciable, the requirement of large single crystals may be obviated.
93623The thermal dissociation of CIFa behind incident shock waves has been studied in the temperature range of 800-1300°K. The course of the dissociation was followed by means of ultraviolet absorption spectroscopy centered a t 2200 =k 250 A. Initial slope measurements gave a value of kl = 101a.5*'J-4 exp -[(28,200 f 1700)/ R T ] cc/mol sec for the rate constant of the reaction CIFa + M = C1F2 + F + M. The collision efficiency of ClF relative to argon was found to be 35 =k 5 to 1. Evidence is presented which favors a heat of formation for CIFz of -19 =t 2 kcal/mol a t OOK.
The vibrational excitation of HF occurring behind incident shock waves has been studied in the temperature range of 1400°K to 4100'K. The extent of excitation was determined as a function of time by continuously monitoring the emission intensity from the 1-0 band of HF centered at 2.5 p. The data were interpreted in terms of the process for M = HF. parison to this result. tion rate, i.e., it was found thatThe corresponding result for ( T~) T ; was found to be insignificant in comData were also obtained for the effect of F atoms upon the relaxa-( @ ) H F / ( T~) F -18 f I
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