Nitrogen, solid free energy

Figure 2. Equilibrium concentrations in mole fractions of selected compounds at 500°K. and 1 atm. with composition of 40% oxygen, the indicated percentage of carbon, and the rest hydrogen. To this basic composition is added an amount of nitrogen equal to the amount of carbon. The nitrogen remains primarily as N2 but produces significant quantities of some interesting compounds. The free energy of carbon in the system equals that of graphite at the composition indicated by the arrow. At this point solid carbon would be precipitated if it could be formed there is no inflection of the curves at this point. The asphalt threshold is shown as a sharp inflection, sharpest of all for the aromatic and related heterocyclic compounds. If an atmosphere such as this were to condense, there would be about 1 molecule of glycine per droplet of condensate (6).

RT log K, where K—pmJPp Pvi- The free energy of the formation of phosphine from hydrogen and solid phosphorus at 25° is —3296-0 cals. The entropy change in the reaction calculated from the free energy equation is —27-72 so that the entropy of phosphine at 25° is 52-4 units. J. C. Thomlinson compared the heats of formation of the trihydrides of the nitrogen-antimony family of elements. 

Nitrogen forms several oxides, in wbicb it exhibits positive oxidation states of 1 to 5 (Table 24-8). All have positive free energies of formation, owing to the high dissociation energy of N2 and O2 molecules. All are gases except N2O5, a solid that melts at 30.0°C. 

The National Bureau of Standards Report 6928 lists the properties of compounds of lithium, beryllium, magnesium, and aluminium with hydrogen, oxygen, fluorine, chlorine, nitrogen, and carbon. Thermodynamic functions for the ideal gases, solids, and liquids are tabulated (e.g. values of free energy functions and enthalpy functions , entropy, and heat capacity). 

Marsh and Rand critically appraise the D-R equation and state that it predicts a Raleigh distribution of adsorption free energy, and only when this distribution is present in microporous solids will a completely linear plot result. Adsorption of carbon dioxide, nitrogen and argon at 77 K on various microporous carbons were examined and in no case was the complete Raleigh distribution found to apply. In order to obtain meaningful parameters they recommended that the experimental data be extended to as near unit relative pressure as possible [76,77]. 

One of the simplest quantitative models was proposed by Horvath and Kawazoe (ref. 12) developed for adsorption in active carbons. It is employed in these studies to compare different zeolites, but, recognizing the differences between active carbons and zeolites, it is only a qualitative measure of pore dimensions. This method (denoted "H-K ) is based on statistical thermodynamics of the adsorbed gas molecules on surfaces. They use a 10-6 Lennard-Jones potential model to relate the free energy of a sorbed gas molecule to the distance between the gas molecule and solid surface. The smallest pore size is constrained by the diameter of the sorbent molecule (e.g., for nitrogen 3.65 A). Sensitivity increases with decreasing pore size. The comparison between the pore size predicted by the Kelvin and H-K theories is shown below in figure 1. 

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