ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The pure salts Na2S2, K2S2, K2S3, Na2S4, K2S4 and K2S5 have been prepared. Titration curves of these polysulfides in aqueous solution have been obtained with a special streaming apparatus, with which the mixing of the polysulfide solution with HCl and the pH determination of the fresh mixture is accomplished within 10-2 seconds. This time is too short for decomposition of the protonated polysulfide anions into sulfur and monosulfide or H2S respectively to occur. With K2S5 the buffer regions S52- ⇄ HS5- ⇄ H2S5 were obtained readily, furnishing the pK's of H2S5. The solutions of the lower polysulfides, however, do not contain simply the anions present in the lattice of the solid salt. As soon as the solid salts are dissolved disproportionation reactions take place giving rise to mixtures. From the protonation curves of these mixtures - taken with the streaming device mentioned - their composition can be deduced, and it was found that all solutions contain the ions OH-, SH-, S42- and S52-. The ions S22- and S32- were never detected. The equilibrium between mono-, tetra- and pentasulfide has been elucidated and the pK's of H2S4 have been obtained. The results have been checked with photometric measurements on the polysulfide solutions.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19600430521
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