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Issue 7, 2008
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Speciation studies in aqueous HCO3–CO32− solutions. A combined Raman spectroscopic and thermodynamic study

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Abstract

Raman (and a few additional FT-IR) spectroscopic measurements of sodium and potassium carbonate and hydrogencarbonate in aqueous solution have been carried out over wide concentration ranges at room temperature and at elevated temperatures. The bands of the CO32−(aq) and HCO3(aq) species, which possess pseudo D3h and C1 symmetry respectively, have been assigned and discussed. Quantitative Raman measurements and thermodynamic calculations on KHCO3 solutions show that the salt does not dissolve congruently in aqueous solutions but forms small amounts of CO32−. Quantitative Raman spectroscopic measurements have also been carried out on K2CO3 solutions and the hydrolysis of the carbonate ion has been determined as a function of concentration at room temperature and as a function of temperature up to 219 °C. The pK2 value of carbonic acid at 23 °C has been established as 10.35 by Raman spectroscopy, a value that compares favourably with published thermodynamic values.

Graphical abstract: Speciation studies in aqueous HCO3−–CO32− solutions. A combined Raman spectroscopic and thermodynamic study

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Publication details

The article was received on 29 Aug 2007, accepted on 09 Nov 2007 and first published on 10 Dec 2007


Article type: Paper
DOI: 10.1039/B713254A
Citation: Dalton Trans., 2008,0, 900-908
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    Speciation studies in aqueous HCO3–CO32− solutions. A combined Raman spectroscopic and thermodynamic study

    W. W. Rudolph, G. Irmer and E. Königsberger, Dalton Trans., 2008, 0, 900
    DOI: 10.1039/B713254A

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