The stability of the magnesium carbonate ion pair from 10 degrees to 90 degrees C

Siebert, R. M.; Hostetler, P. B.

doi:10.2475/ajs.277.6.716

Cited by 34 publications

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“…The determined constants for the formation of CaCO 3 and MgCO 3 pre-nucleation species in pure systems are in good agreement with previous studies [19][20][21]. In an ideal system without the formation of mixed pre-nucleation clusters, one would expect that Mg 2þ and Ca 2þ containing species act independently from each other, so that the equilibrium constants do not change with altering Mg/Ca-ratios.…”

supporting

confidence: 77%

Mixed calcium-magnesium pre-nucleation clusters enrich calcium

Verch

Antonietti

Cölfen

2012

Zeitschrift Für Kristallographie - Crystalline Materials

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Abstract. It is demonstrated that magnesium and carbonate ions can form pre-nucleation clusters in analogy to calcium carbonate. If a mixed calcium and magnesium solution is brought in contact with carbonate ions, mixed pre-nucleation clusters form. The equilibrium constants for their formation are reported revealing that over the entire range of possible cation mixing ratios, calcium gets enriched over magnesium in the pre-nucleation clusters. This can explain high magnesium contents in amorphous calcium carbonate. However, this enrichment alone is not sufficient to explain the magnesium content of less than 41 mol% which is found in magnesium calcite biominerals nucleated from seawater.

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supporting

confidence: 77%

Mixed calcium-magnesium pre-nucleation clusters enrich calcium

Verch

Antonietti

Cölfen

2012

Zeitschrift Für Kristallographie - Crystalline Materials

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“…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.…”

Section: -18 De Visscher Et Almentioning

confidence: 99%

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

Visscher

Vanderdeelen

Königsberger

et al. 2012

Journal of Physical and Chemical Reference Data

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The alkaline earth carbonates are an important class of minerals. This volume compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1, the present paper, outlines the procedure adopted in this volume in detail, and presents the beryllium and magnesium carbonates. For the minerals magnesite (MgCO 3 ), nesquehonite (MgCO 3 Á3H 2 O), and lansfordite (MgCO 3 Á5H 2 O), a critical evaluation is presented based on curve fits to empirical and=or thermodynamic models. Useful side products of the compilation and evaluation of the data outlined in the introduction are new relationships for the Henry constant of CO 2 with Sechenov parameters, and for various equilibria in the aqueous phase including the dissociation constants of CO 2 (aq) and the stability constant of the ion pair MCO 0 3 ðaqÞ (M ¼ alkaline earth metal). Thermodynamic data of the alkaline earth carbonates consistent with two thermodynamic model variants are proposed. The model variant that describes the Mg 2þ ÀHCO À 3 ion interaction with Pitzer parameters was more consistent with the solubility data and with other thermodynamic data than the model variant that described the interaction with a stability constant.

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Computing SI and CCPP using spreadsheet programs

Holm¹,

Schock²

1998

Journal AWWA

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preadsh eet program s for person al com pu ters are u sefu l for storin g, retrievin g, graph in g, an d reportin g data an d for perform in g repetitiou s calcu lation s. Th ey can be u sed to au tom ate ch em ical equ ilibriu m calcu lation s th at can be perform ed by h an d, i.e., system s of equ ation s th at can be solved in closed form or with reason able sim plifyin g approxim ation s. Su ch problem s, h owever, are u su ally limited to a few u n kn own s. For exam ple, th e calcite satu ration in dex (SI cal ) in dicates th e ten den cy of water to precipitate or dissolve CaCO 3 . At pH valu es of m ost potable water sou rces, th e Langelier in dex 1 (LI) closely Lo tu s 1-2-3® w o rk sh e e ts fo r calcu latin g th e calcite satu ratio n in d e x (SI) an d calciu m carbo n ate p re cip itatio n p o te n tial o f a w ate r sam p le are d e scribe d . A sim p lifie d w o rk sh e e t illu strate s th e p rin cip le s o f th e m e th o d , an d a m o re co m p le x w o rk sh e e t su itable fo r m o d e lin g m o st p o table w ate r so u rce s is brie fly d e scribe d . Bo th w o rk sh e e ts in clu d e io n p airin g an d ad ju stm e n ts o f e qu ilibriu m co n stan ts fo r te m p e ratu re an d io n ic stre n gth . Fo r se ve ral te st case s w ith a w id e ran ge o f te m p e ratu re , alk alin ity, p H, an d calciu m co n ce n tratio n , th e w o rk sh e e t SI valu e s d iffe re d <1 p e rce n t fro m th o se co m p u te d by WATEQX. Fo r w ate r qu ality m o d e lin g, sp re ad sh e e ts h ave se ve ral ad van tage s co m p are d w ith large e qu ilibriu m co d e s: fle x ible in p u t an d o u tp u t, e ase o f m ain tain in g th e th e rm o d yn am ic d atabase , an d re lative ly sm all m e m o ry an d m ass-sto rage re qu ire m e n ts. Mo d e lin g o f arch ive d ch e m ical d ata is p o ssible th ro u gh th e co m bin atio n o f d atabase m an age m e n t an d co m p u tatio n al cap abilitie s o f m an y co m m e rcially available p ro gram s. Th e w o rk sh e e ts can be o btain e d fro m th e au th o rs.

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The stability of the magnesium carbonate ion pair from 10 degrees to 90 degrees C

Cited by 34 publications

References 0 publications

Mixed calcium-magnesium pre-nucleation clusters enrich calcium

Mixed calcium-magnesium pre-nucleation clusters enrich calcium

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

Computing SI and CCPP using spreadsheet programs

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