Nitric acid, activity coefficient

Feed and removal volumetric flow Concentration of hexamine in feed Molar mass of hexamine Concentration of nitric acid in feed Molar mass of nitric acid Pre-exponential factor Apparent energy of activation Order of the reaction Thermal capacity of hexamine Feed temperature of hexamine Thermal capacity of nitric acid Feed temperature of nitric acid Overall coefficient of heat transfer Area for heat transfer (jacket + coU) Enthalpy of reaction Reaction temperature... 

As the medium is still further diluted, until nitronium ion is not detectable, the second-order rate coefficient decreases by a factor of about 10 for each decrease of 10% in the concentration of the sulphuric acid (figs. 2.1, 2.3, 2.4). The active electrophile under these conditions is not molecular nitric acid because the variation in the rate is not similar to the correspondii chaise in the concentration of this species, determined by ultraviolet spectroscopy or measurements of the vapour pressure. " ... 

Considering first pure nitric acid as the solvent, if the concentrations of nitronium ion in the absence and presence of a stoichiometric concentration x of dinitrogen tetroxide are yo and y respectively, these will also represent the concentrations of water in the two solutions, and the concentrations of nitrate ion will be y and x- y respectively. The equilibrium law, assuming that the variation of activity coefficients is negligible, then requires that ... 

Nitration by nitric acid in sulphuric acid has also been by Modro and Ridd52 in a kinetic study of the mechanism by which the substituent effects of positive poles are transmitted in electrophilic substitution. The rate coefficients for nitration of the compounds Pl CHi NMej (n = 0-3) given in Table 10 show that insertion of methylene groups causes a substantial decrease in deactivation by the NMej group as expected. Since analysis of this effect is complicated by the superimposed activation by the introduced alkyl group, the reactivities of the... 

Studies of the reaction between various substituted benzenes and nitric acid, which can take place in a number of different acid systems, have been reported in an extensive series of papers by the Marziano group, using correlations with the Me activity coefficient function. This reaction is a two-stage process,... 

If, for example, a mixture of ethanol and water is distilled, the concentration of the alcohol steadily increases until it reaches 96 per cent by mass, when the composition of the vapour equals that of the liquid, and no further enrichment occurs. This mixture is called an azeotrope, and it cannot be separated by straightforward distillation. Such a condition is shown in the y — x curves of Fig. 11.4 where it is seen that the equilibrium curve crosses the diagonal, indicating the existence of an azeotrope. A large number of azeotropic mixtures have been found, some of which are of great industrial importance, such as water-nitric acid, water-hydrochloric acid, and water-alcohols. The problem of non-ideality is discussed in Section 11.2.4 where the determination of the equilibrium data is considered. When the activity coefficient is greater than unity, giving a positive deviation from Raoult s law, the molecules of the components in the system repel each... 

Clegg, S. L, and P. Brinibleconibe, Equilibrium Partial Pressures and Mean Activity and Osmotic Coefficients of 0-100% Nitric Acid as a Function of Temperature, J. Phys. Chem., 94, 5369-5380 (1990), and references therein. 

Nitric acid is a strong electrolyte. Therefore, the solubilities of nitrogen oxides in water given in Ref. 191 and based on Henry s law are utilized and further corrected by using the method of van Krevelen and Hofhjzer (77) for electrolyte solutions. The chemical equilibrium is calculated in terms of liquid-phase activities. The local composition model of Engels (192), based on the UNIQUAC model, is used for the calculation of vapor pressures and activity coefficients of water and nitric acid. Multicomponent diffusion coefficients in the liquid phase are corrected for the nonideality, as suggested in Ref. 57. 

Clegg SL, Brimblecombe P (1990a) Equilibrium partial pressures and mean activity and osmotic coefficients of 0-100% nitric acid as a function of temperature. J Phys Chem 94 5369-5380 Clegg SL, Brimblecombe P (1990b) The solubility and activity coefficient of oxygen in salt solutions and brines. Geochim Cosmochim Acta 54 3315-3328... 

Figure 5. Activity coefficient of nitric acid in mixed acid...

In the U.S.S.R., the D.V.S. is often named the coefficient of dehydration and a slightly different way of calculating the nitric composition of sulphuric acid mixtures is in use there. This is

nitrating activity suggested by Kholevo. According to Gorst [2], it is the concentration of sulphuric acid in the mixture when the nitric acid is converted into the equivalent quantity of water. 

The extraction of Bk(III) by phosphoorganic acids has been studied, and activity coefficients for Bk(III) in nitric acid solution were estimated (204). In addition, a mechanism for the extraction of Bk(IV) by hydrogen di(2-ethylhexyl)orthophosphoric acid (HDEHP) from nitric acid solutions was proposed. 

In this chapter the thermodynamic analysis of the Nd(N03)3-HN03-H20 system is presented. The determination of the activity and the activity coefficient of the free neodymium (III) ion and the development of an accurate model for the activity behavior of aqueous binary electrolyte solutions consisting of the neodymium nitrate and nitric acid are presented. 

Bates and Alfenar (23) proposed that the activity of the chloride ion in NaCl solutions be taken as the activity standard. Using this chloride convention together with the published values of mean activity coefficients, the activity of any simple ionic species can be estimated. The equation used to estimate values of yNo3 and thus aNo3 for nitric acid solutions is... 

Table II. Data for the Calculation of the Nitrate Ion Activity Coefficient in Aqueous Solutions of Nitric Acid...

Figure 2. Activity coefficients of HNOs and NOs as a function of the molar nitric acid concentration...

The bare proton has an exceedingly small diameter compared with other cations, and hence has a high polarising ability, and readily forms a bond with an atom possessing a lone pair of electrons. In aqueous solution the proton exists as the H30+ ion. The existence of the H30+ ion in the gas phase has been shown by mass spectrometry [4], and its existence in crystalline nitric acid has been shown by NMR [5], Its existence in aqueous acid solution may be inferred from a comparison of the thermodynamic properties of HC1 and LiCl [6]. The heat of hydration of HC1 is 136 kcal mole"1 greater than that of LiCl, showing that a strong chemical bond is formed between the proton and the solvent, whereas the molar heat capacity, molar volume and activity coefficients are similar,... 

As far as the activity of the nitrating mixture (Vol. I, p. 29) is concerned, a novel approach to the problem was recently developed by Marziano and associates [13]. In a series of papers on thermodynamic analysis of nitric acid with sulphuric or perchloric acid these authors introduced a new function of the activity coefficient... 

Using the literature data for the concentrations of the non-hydrated acid in the HN03-H20 system, its states in the HN03-H2S04-H20 system, and its partial vapour pressures, the applicability of Henry s law has been demonstrated to non-hydrated nitric acid in these systems.128 On the basis of a study129 of the systems HN03-H20-M(N03)n (MB+ = Na+, Cu2+, Be2+, U02+, La3+, Fe3+, or Al3+), the salting-out activity of the nitrates is characterized by the separation coefficient I described by ... 

The authors prepared Al2(Se03)3(s), Ga2(Se03)3(s), In2(Se03)3(s), and Tl2(Se03)3(s). The solubilities of the salts were measured in nitric, perchloric, or sulphuric acid at 298 K. No primary experimental data are furnished and the review assumes that the pH values, 1.7 to 2.0, reported refer to the saturated solutions. The solubility products were calculated from the analytical concentration of dissolved metal ion with corrections for the protonation of the selenite ion and the activity coefficients. No recalculation with the values of these quantities accepted by the review is possible. 

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