Hydrogen chloride thermodynamic data

In the authors opinion, the thermodynamic data presented show that the whole of the concentration region studied can be treated from the viewpoint of the formation of MgCl - coordination compounds in the melts. Dissolution of hydrogen chloride in the melts is not accompanied by an appreciable interaction with the melt components (KC1 and MgCl2). Therefore, the work of the formation of the void in the melts should be the main factor, which defines the behaviour of the temperature dependence. The changes in the deviation of the derived AH and AS values from the additive magnitudes possess an extremal character the maximum deviations are observed at an... 

The following data, taken from the National Bureau of Standards compilation. Selected Values of Chemical Thermodynamic Properties gives the standard enthalpy of formation of hydrogen chloride from its elements at 25 °C in kg cal mol (Thus the difference between the first and third results gives the heat of dissolving 1 mol of HCl gas in 2 mol of water.) Show that the partial molar enthalpy of hydrogen chloride in a 10 mol dm solution, relative to the elements, is —36.26 kg cal mol , and that the partial molar enthalpy of water in the same solution, relative to pure liquid water, is —0.43 kg cal mol. ... 

Frederick D. Rossini, Heat of Formation of Hydrogen Chloride and some Related Thermodynamic Data. J. Res. Natl. Bur. Stand. (U.S.), 9,679-702 (1932). 

The definition of suitable indicator electrodes forms the basis of both theoretical and practical aspects of e.m.f. measurements, e.g. for obtaining basic thermodynamic data, elucidation of electrode processes and in situ analyses. The three that meet the requirements most adequately are the hydrogen electrode (q.v.), the silver-silver chloride electrode (q.v.) and the calomel electrode (q.v.). The only electrode to which the term reference electrode may be rigorously applied is the hydrogen electrode. Of the secondary electrodes, a distinction is drawn between those for which the standard potential can be expressed in terms of strictly thermodynamic quantities and those which are less easily explained on purely thermodynamic principles, e.g. the glass electrode (q.v.). 

However, the fact that HOCl is a weak acid, while HCIO3 and HCl are strong ones (see Table 6.3) means that, in the presence of hydrogen ions, [OCl] is protonated and this affects the position of equilibrium 16.81 HOCl is more stable with respect to disproportionation than [OCl]. On the other hand, the disproportionation of chlorate into perchlorate and chloride is realistically represented by equilibrium 16.82. From the data in Figure 16.9, this reaction is easily shown to be thermodynamically favourable (see problem 16.18b at the end of the chapter). Nevertheless, the reaction does not occur in aqueous solution owing to some undetermined kinetic factor. 

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