Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile

P. B. Hostetler; C. L. Christ

Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile

P. B. Hostetler^*, C. L. Christ

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

21 Citations (Scopus)

Abstract

Chrysotile dissolves congruently in water according to the reaction: Mg₃Si₂O₆(OH)_4c + 5H₂O_l = 3Mg_aq ²⁺ + 6OH_aq ^- + 2H₄SiO_4aq. Experimental determination of the activity-product constant of chrysotile, K_chr = [Mg²⁺]³[OH^-]⁶[H₄SiO_4aq]², at 90°C, yields the value of K_chr = 10^-49.2 ± 10^0.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of K_chr were calculated for temperatures ranging from 0°C to 200°C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). K_chr is 10^-54.1 at 0°C, rises to a maximum value of 10^-48.5 at approximately 135°C, and is 10^-49.1 at 200°C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90°C value is 10^-49.1, in excellent agreement with the experimental value; for 25°C, the calculated value is 10^-50.8.

Original language	English
Pages (from-to)	485-497
Number of pages	13
Journal	Geochimica et Cosmochimica Acta
Volume	32
Issue number	5
Publication status	Published - May 1968
Externally published	Yes

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title = "Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile",

abstract = "Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq 2+ + 6OHaq - + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90°C, yields the value of Kchr = 10-49.2 ± 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0°C to 200°C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0°C, rises to a maximum value of 10-48.5 at approximately 135°C, and is 10-49.1 at 200°C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90°C value is 10-49.1, in excellent agreement with the experimental value; for 25°C, the calculated value is 10-50.8.",

author = "Hostetler, {P. B.} and Christ, {C. L.}",

year = "1968",

month = may,

language = "English",

volume = "32",

pages = "485--497",

journal = "Geochimica et Cosmochimica Acta",

issn = "0016-7037",

publisher = "Elsevier",

number = "5",

}

TY - JOUR

T1 - Studies in the system MgO-SiO2-CO2-H2O(I)

T2 - The activity-product constant of chrysotile

AU - Hostetler, P. B.

AU - Christ, C. L.

PY - 1968/5

Y1 - 1968/5

N2 - Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq 2+ + 6OHaq - + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90°C, yields the value of Kchr = 10-49.2 ± 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0°C to 200°C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0°C, rises to a maximum value of 10-48.5 at approximately 135°C, and is 10-49.1 at 200°C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90°C value is 10-49.1, in excellent agreement with the experimental value; for 25°C, the calculated value is 10-50.8.

AB - Chrysotile dissolves congruently in water according to the reaction: Mg3Si2O6(OH)4c + 5H2Ol = 3Mgaq 2+ + 6OHaq - + 2H4SiO4aq. Experimental determination of the activity-product constant of chrysotile, Kchr = [Mg2+]3[OH-]6[H4SiO4aq]2, at 90°C, yields the value of Kchr = 10-49.2 ± 100.5. A synthetic sample and a natural sample from New Idria, California, were used in the determination. Values of Kchr were calculated for temperatures ranging from 0°C to 200°C, using the thermochemical data of King et al. (1967) for chrysotile and antigorite, various solubility data for silica, and ionic partial molal heat capacities estimated by the method of criss and Cobble (1964a). Kchr is 10-54.1 at 0°C, rises to a maximum value of 10-48.5 at approximately 135°C, and is 10-49.1 at 200°C (all values for the three-phase system, chrysotile plus solution plus vapor). The calculated 90°C value is 10-49.1, in excellent agreement with the experimental value; for 25°C, the calculated value is 10-50.8.

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M3 - Article

AN - SCOPUS:4243333218

VL - 32

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JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

IS - 5

ER -

Studies in the system MgO-SiO2-CO2-H2O(I): The activity-product constant of chrysotile

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