Journal of Solution Chemistry

, Volume 10, Issue 4, pp 269–279 | Cite as

Thermodynamics of the dissociation of Bis H+ in seawater from 5 to 40°C

  • Roger G. Bates
  • James G. Calais


Electromotive-force measurements of cells without transference were used to determine the dissociation constant of the protonated form of the weak base 2-amino-2-methyl-1, 3-propanediol (Bis) in synthetic seawaters corresponding to salinities of 20, 35, and 45‰. Hydrogen electrodes and silver-silver chloride electrodes were used, together with standard potentials determined in an earlier investigation. The pK increases in linear fashion with the salinity (S) of the medium, for values of S from 0 to 45‰. The solvent effect is given by 8.802+0.00378S at 25°C with a mean deviation of 0.001. The medium effect of seawater on ΔH° at 25°C is less than 200 cal-mol−1 and less than 0.2 cal-oK-mol−1 on ΔS°.

Key words

Acidic dissociation Bis dissociation dissociation constant ion-ion interactions ionization seawater thermodynamics of dissociation 


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Copyright information

© Plenum Publishing Corporation 1981

Authors and Affiliations

  • Roger G. Bates
    • 1
  • James G. Calais
    • 1
  1. 1.Department of ChemistryUniversity of FloridaGainesville

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