The Dissociation Pressures of Hydrated Double Salts

Ferguson, John (1925) The Dissociation Pressures of Hydrated Double Salts. PhD thesis, University of Glasgow.

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Abstract

1. The hydrates formed by double sulphates and selenates of the types: RSO4, M2SO4, 6H2O and RSeO4, M2SeO4 6H2O have been investigated. As far as has been investigated, the iron and magnesium salts first form tetrahydrates on loss of water, all the other salts forming dihydrates. 2. An induction lag in the dehydration of the hexa-hydrated salts has been studied. 3. The dissociation pressures of the hexahydrated salts in equilibrium with their next lower hydrates have been measured over a range of temperatures. 4. The stabilities of the hydrates, as indicated by the absolute temperatures at which the pressure attains a value of 50 mm., show a close relation with the molecular volumes of the salts, and with the atomic volumes of their constituents. 5. The stabilities of the hydrates increase with diminishing volume of the negative portion of the molecule considering the sulphate and selenate groups separately. 6. The stabilities of the hydrates show a tendency to increase with increasing volume of the positive portion of the molecule except in the case of caesium, the general order being K, Cs, Rb, NH4, in the case of the sulphates, and Cs, K, Rb, NH4 in the case of the selenates When the bivalent metal is either copper, cadmium, or manganese, the order is K, Rb, NH4, Cs, in the case of the sulphates. 7. These relations are the opposite of what obtains with that other large class of auxiliary valency compounds - the inorganic ammines. 8. The ammonia and thallium salts furnish dissociation pressures which, in magnitude, approach more nearly to those of the rubidium salts than those of the potassium and caesium salts. This relationship to rubidium is in accord with the results of Tutton (loc. cit. ), and is considered due to the similarity in molecular volume of the rubidium, ammonium, and thallium salts.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Inorganic chemistry
Date of Award: 1925
Depositing User: Enlighten Team
Unique ID: glathesis:1925-80998
Copyright: Copyright of this thesis is held by the author.
Last Modified: 31 Mar 2020 11:36
URI: http://theses.gla.ac.uk/id/eprint/80998

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