Bicarbonate and carbonate ion‐pairs and a model of seawater at 25°C1

Abstract

The apparent (stoichiometric) association constants for the formation of ion-pairs between bicarbonate and carbonate and the major cations of seawater at 25°C were dctcrmined experimentally.The results wcrc used, in conjunction with earlier data on sulfate ion-pairs, to calculate the concentrations of the major species present in scawatcr.Here we measured the apparent (stoichiometric) association constants for the formation of bicarbonate and carbonate ion-pairs with sodium, calcium, and magnesium ions at 25°C and 0.72 ionic strength. The results were used, in conjunction with the sulfate association constants determined by Kester and Pytkowicz ( 1969)) to detcrmine the major ionic species present in seawater at 25°C and 34.8z0 salinity. We will show later that the proportions of ion-paired and free species are insensitive to the salinity.Activity coefficients are lower and solubility products higher in some mixed elcc-.trolyte solutions such as seawater than in chloride solutions ( Kester and Pytkowicz 1969). This is usually attributed to ionic interactions, which can range from the formation of ion-pairs (outer sphere interactions due to electrostatic attraction) to that of true complexes (inner sphere bonds with loss of water of hydration).Partial molal volume data (Kestcr 1969) and results from Raman spectra (Daly et al. 1972) suggest that the major ions of seawater may form ion-pairs, although the potentiometric method we used does not distinguish between ion-pairs and complexes.

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

“…Data of Neuman et al, 64 Hostetler, 65 Langmuir, 66 Nakayama, 67 Jacobson and Langmuir, 63 Martynova et al, 68 Pytkowicz and Hawley, 69 Siebert and Hostetler, 70 Plummer and Busenberg, 27 Le Guyader et al, 71 Busenberg et al, 72 and Busenberg and Plummer 73 are listed. The tabulated values are not very consistent, as was also observed by Burton.…”

“…Based on this idea, and the data of Table 8, an equation of the form A þ B=T was fitted to the data, transformed to Eq. (94) 69 were discarded as they reported stoichiometric instead of thermodynamic constants and the results deviated by almost an order of magnitude from other data; for lg K CaHCO þ 3 , the datum of Neuman et al 64 was discarded because the temperature of the experiment was not reported, 013105-19 IUPAC-NIST SOLUBILITY DATA SERIES. 95-1 and because of deviation from the other data.…”

“…An overview of these and other literature values is given in Table 9. Values of Nakayama, 67 Nakayama and Rasnick, 80 Lafon, 81 Beneš and Selecká, 82 Martynova et al, 68 Pytkowicz and Hawley, 69 Reardon and Langmuir, 83 Siebert and Hostetler, 84 Plummer and Busenberg, 27 Le Guyader et al, 71 and Busenberg and Plummer 73 are listed.…”

“…(85) were determined for the stability constants of the MCO 0 3 ion pairs. The data of Greenwald 62 were not used due to deviations from other data for Mg, and due to the critique of Jacobson and Langmuir; 63 data of Pytkowicz and Hawley 69 were not used because of the difference with the other data, and because the values are stoichiometric, not thermodynamic; data of Nakayama 67 were discarded due to large deviation from other data, and the critique of Jacobson and Langmuir; 63 data of Martynova et al 68 were discarded due to lack of clarity of the methods used, and due to inconsistency with other data; data of Le Guyader et al 71 and Beneš and Selecká 82 were discarded due to large deviation from other data. The coefficients of Eq.…”

Investigation of the 1kHz sound absorption in sea water

“…It must be remembered that artificial sea water without boric acid demonstrated no low frequency relaxation frequency. As indicated in Table 6, the relaxation frequencies indicate no major variation until NaHCO, Garrels and Thompson (1962) and reviewed by Pytkowicz and Hawley (1974) and Whitfield (1974 As previously noted, Dyrssen and Hansson (1973) and Byrne and Kester (1974) Table 9. Using these data, the rate constants and equilibrium 117 Ill constants for the second step of equation were calculated using procedures previously described.…”