Hydrogen sulfide equilibrium constant

Figure 4-4. Vapor-solid equilibrium constants o) for carbon dioxide, b) for hydrogen sulfide. (From Gas Processors Suppliers Association, Bngineerinq Data Book, 10th Edition.)...

This reaction is characterized by a high value of the equilibrium constant (1.7 10s), pointing thereby to the efficacy of lime in scavenging hydrogen sulfide. With lime incorporated, the final reaction is given by... 

The release to the atmosphere is strongly dependent on the pH because only the molecular form and not the dissociated forms can be emitted, e.g., at a pH about 7, an equal amount of H2S and HS- exists in the water phase. Increase of the pH will, therefore, at equilibrium conditions and at a constant total sulfide concentration, reduce the hydrogen sulfide concentration in the overlying sewer atmosphere (Figure 4.1). Therefore, when applying Henry s law [Equation (4.8)], only the nondissociated molecular form, H2S, should be taken into account. 

To calculate the multicomponent vapor-liquid equilibrium, equilibrium constants for chemical reactions 1-9 are taken from literature in comparison to the original publication, in the present work different numerical values for the second dissociations of hydrogen sulfide and sulfur dioxide were chosen (cf. Appendix III). Henry s constants are evaluated from single solute solubility data without neglecting Poynting corrections ... 

A. System NH3 H S-H20. The dissociation of water (re-action 9) and the second dissociation of H2S (reaction 6) are neglected at given temperature and total molalities of NHo and H2S there remain four unknown molalities in the liquid phase (e.g. NH3, NH4+, H2S and HS ), the composition of the vapor phase and the total pressure, which are calculated from 8 equations The dissociation constants of ammonia and hydrogen sulfide (eqs.I and III) together with the phase equilibrium for hydrogen sulfide (eq. XII) are combined resulting in a equilibrium constant K 2... 

The temperature dependency of equilibrium as well as of Henry s constants is given in tables A II.I and A II.II (cf. Appendix II). In comparison with the original publication for the equilibrium constants of the second dissociations of hydrogen sulfide and sulfur dioxide (reactions 6 and 7) numbers derived from Cobble (18) and Arkhipova et al. (J 9) were used. 

Chemical Properties. Although hydrogen sulfide is thermodynamically stable, it can dissociate at very high temperatures. The decomposition thermodynamics and kinetics have been reviewed and the equilibrium constant for the reaction has been determined (101,102) ... 

The equilibrium constant is 0.013 at 18°C. Sulfur dichloride reacts violently with water, forming hydrogen chloride, sulfur dioxide, hydrogen sulfide, sulfur, and a mixture of thionic acids. 

The equilibrium constant does, however, decrease with increasing temperature for each particular reaction but still does retain a substantially positive value at 425°C (795°F) which is approaching the maximum temperature at which many of the hydrodesulfurization (especially nondestructive) reactions would be attempted. The data also indicate that the decomposition of sulfur compounds to yield unsaturated hydrocarbons and hydrogen sulfide is not thermodynamically favored at temperatures below 325°C (615°F) and such a reaction has no guarantee of completion until temperatures of about 625°C (1155°F) are reached. However, substantial decomposition of thiols can occur at temperatures below 300°C (570°F) in fact (with only few exceptions), the decomposition of all saturated... 

To determine whether a change in dispersion or in the type of catalytic sites is responsible for these different effects of phosphate, Jian and Prins (59, 75) investigated the kinetics of these hydrogenation and elimination reactions. Unfortunately, no simple chemisorption method has proved capable of determining the dispersion of supported metal sulfides (6). Therefore, an indirect method, involving the determination of rate and adsorption equilibrium constants (the first proportional to the number of sites and the second dependent only on the type of site) had to be used. 

Heteroatomic nucleophiles which also have been shown to undergo addition across the 3,4-double bond of quinazolines 5 and with which the addition products 6 were isolated include the methoxide anionand sodium hydrogen sulfite.(For addition of sodium hydrogen sulfite and hydrazine at the 4-position of quinazoline 3-oxides with concomitant deoxygenation of the A(-oxide group, cf p 105.) Equilibrium and rate constants have been determined at 25 °C for the covalent addition of water, the bisulfite ion, hydroxylamine, urea, 2-sulfanylethanol, and hydrogen sulfide to the 3,4-bond of the quinazoline cation. ... 

At 1405 K, hydrogen sulfide, also called rotten egg gas because of its bad odor, decomposes to form hydrogen and a diatomic sulfur molecule, 2. The equilibrium constant for the reaction is 2.27 x 10 . ... 

The removal of substances having reasonable equilibrium vapor pressures at ambient temperatures, including ammonia, carbon dioxide, hydrogen sulfide, and many VOCs (volatile organic compounds), by any of the processes known as air or gas stripping has proven to be efficient and cost effective. The Henry s law constant is a primary indicator of a compound s potential for removal by air stripping. 

Sulfur dioxide, SO2, one of the intermediates in the production of sulfuric acid, can be made from the reaction of hydrogen sulfide gas with oxygen gas. Write the equilibrium constant expressions for Kc and Kp for the following equation for this reaction. 

Table 8.8 presents these numbers in a slightly different way, in which the equilibrium constant is multiplied by the pressure term to whatever power is appropriate and the result is the ratio of naphthenes to aromatics, calculated for four temperatures—400°F, 600°F, 800°F, and 1000°F—at 2500 psi hydrogen partial pressure. High values of Keq pH2 correspond to low aromatic levels and are favored by low temperatures, hence the use of highly active noble metals and nickel catalysts for this purpose. Base metal sulfide catalysts have also been successfully used for this purpose, but are less likely to achieve very low product polyaromatic levels. 

Figure 11 Illustrates a simplified arrangement of components and the magnitude of operating parameters for the concentration of deuterium by dual-temperature exchange between hydrogen sulfide gas and liquid water. H2S Is circulated In a closed loop counter-current to a descending stream of water. In the colder column deuterium concentrates In the liquid phase the equilibrium constant for the exchange at the cold temperature, 30°C, is 2.20.

D2. We are absorbing hydrogen sulfide at 15°C into water. The entering water is pure. The feed gas contains 0.0012 mole frac hydrogen sulfide and we want to remove 97% of this in the water. The total gas flow rate is 10 kmol/h. The total liquid flow rate is 2000 kmol/h. Total pressure is 2.5 atm. You can assume that total liquid and g s flow rates are constant. Equilibrium data are in Table 12-1. 

Krupp RE (1988) solubility of stibnite in hydrogen-sulfide solutions, speciation, and equilibrium-constants, from 25 to 350-degrees-C. Geochim Cosmochim Acta 52 3005-3015 Kumar PV, Tembe BL (1992) Solvation stracture and dynamics of the Fe -Fe ion-pair in water. J Chem Phys 97 4356-4367... 

The equilibrium constant only depends on the partial pressure of the steam and hydrogen sulfide ... 

Experimentally determined vapor-liquid equilibrium data for the system hydrogen sulfide-carbon dioxide-methane-water at pressures ranging from atmospheric to 1,014 psia and temperatures from 85° to 115°F have been reported by Froning et al. (1964). These authors found that the equilibrium constants K can be represented by the following equations ... 

---