The solubility of Ca(OH) 2 in extremely concentrated NaOH solutions at 25°C

Attila Pallagi, Agost Tasi, Attila Gácsi, Miklós Csáti, István Pálinkó, Gábor Peintler, Pál Sipos

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15 Citations (Scopus)


The solubility of Ca(OH) 2 in aqueous NaOH solutions up to 12.50 M at 25°C has been determined. The solubility data obtained for NaOH concentrations lower than 3 M was compared with those published in the literature. The solubility of Ca(OH) 2 steadily decreases with the increasing NaOH concentration. The solubility data obtained at a constant ionic strength (I = 1 M Na(Cl,OH)) enabled the determination of the conditional solubility product of Ca(OH) 2(s) (lgLCa(OH) 2 = - 4.10 ± 0.02). Formation of the hydroxo complex CaOH+(aq) was invoked to describe the variation of [Ca2+]T with [OH-]T. Its conditional stability constant was found to be lgKCaOH+ = 0.97 ± 0.02. The experimental protocol employed was proven to be suitable for accurate solubility determinations in rapidly equilibrating systems comprising of highly concentrated, alkaline solutions and containing analytes in the ppm range.

Original languageEnglish
Pages (from-to)332-337
Number of pages6
JournalCentral European Journal of Chemistry
Issue number2
Publication statusPublished - Apr 1 2012


  • Aqueous solutions
  • Ca(OH)
  • Concentrated electrolytes
  • Solubility
  • Solubility apparatus

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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