ISSN:
1572-8927
Keywords:
Aqueous solution
;
activity coefficient
;
emf
;
temperature dependence
;
H2S
;
NaHS
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Values for the mean stoichiometric activity coefficient of NaHS in the system NaHS−H2S−H2O are presented from 12 to 83°C for NaHS concentrations up to 0.2m and for H2S fugacities up to 1 atm. The measurements were made potentiometrically using a novel approach employing three commercially available specific ion electrodes (Na+ glass, H+ glass, and Ag2S) combined to form two cells without liquid junction. The results are described by the equation t(°C) D B° ΔB 10 0.223 0.075 0.442 25 0.151 0.006 0.248 80 0.024 0.326 0.180 Where γ ± * is the mean activity coefficient relative to a standard state in which γ ± * →1 asm NaHS→0 and $$m_{H_2 S} \to 0$$ . As expressed by this equation, an increase in the fugacity (or activity) of H2S causes the activity coefficient of NaHS to increase at constantT, P, andm NaHS, the effect becoming more pronounced at lower temperatures. It is suggested that H2S causes the solvent molecules to adopt a quasi-clathrate structure producing partial deslvation and destabilization of Na+ and HS− ions. Hydrogen sulfide is known to form a stable clathrate compound just above 0°C when $$P_{H_2 S} = 1 atm$$ . The bisulfide ion appears to be a structure promotor based upon the value of the NaHS activity coefficient relative to those of other proton-accepting anions such as OH−, HCO in3 − , and acetate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01167238
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