An approximation of the second dissociation constant for H sub 2 S

Journal Article · Mon Feb 29 23:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90326-2· OSTI ID:5221257

Schoonen, M A.A.; Barnes, H L ^[1]

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1. Pennsylvania State Univ., University Park (USA)

Poor resolution of {Delta}G{sup 0}{sub f} for S{sup 2{minus}} affects hydrothermal complexing arguments, evaluation of sulfide solubility products, and calculation of aqueous sulfur speciation. The second dissociation constant for H{sub 2}S (log K{sub HS-}) if well known could be used to determine this free-energy. The log K{sub HS-} has been evaluated here by extrapolating the thermodynamic data for the dissociation of polysulfides (H{sub 2}S{sub n}) as a function of the reciprocal chain length (1/n). The extrapolation method is supported by standard weak acid theory. The extrapolation is further based on flocculation experiments which determined the equilibrium constant for the protonation of a colloidal sulfur surface, which is a reaction analog for the protonation of an infinite sulfur chain, H{sub 2}S{infinity}. The derived log K{sub HS-} value, {minus}18.51 {plus minus} 0.56 (20{degree}C), implies that S{sup 2{minus}} is never a dominant aqueous species. This new value has been used to derive alternative solubility products of some metal sulfides.

• OSTI ID: 5221257
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:3; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
58 GEOSCIENCES
580000* -- Geosciences
BISMUTH COMPOUNDS
BISMUTH SULFIDES
CHALCOGENIDES
CHEMISTRY
COMPLEXES
DISPERSIONS
DISSOCIATION
GEOCHEMISTRY
HYDROGEN COMPOUNDS
HYDROGEN SULFIDES
MIXTURES
PHYSICAL PROPERTIES
SOLUBILITY
SOLUTIONS
STRUCTURAL CHEMICAL ANALYSIS
SULFIDES
SULFUR COMPOUNDS
THERMODYNAMIC ACTIVITY
THERMODYNAMIC PROPERTIES