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The Use of Thermometric Titrations in Soil Chemistry Studies
Author(s) -
Ragland John L.
Publication year - 1962
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1962.03615995002600020012x
Subject(s) - titration , chemistry , potentiometric titration , titration curve , bentonite , conductometry , neutralization , ion exchange , soil water , inorganic chemistry , analytical chemistry (journal) , environmental chemistry , ion , geology , organic chemistry , soil science , paleontology , antibody , immunology , biology
It was determined that a thermometric titration procedure could be used to obtain the cation‐exchange capacities and heats of neutralization of acid‐saturated clays. The endpoints of these titration curves were much sharper than those commonly obtained by potentiometric or conductometric methods. Cation‐exchange capacities calculated from thermometric titration curves of H‐exchanges agreed fairly well with those determined by the BaCl 2 ‐TEA method. Heats of neutralization for Arizona, Mississippi, Southern and Utah bentonites were found to be: −13.3 ±2, −15.9 ±3, −16.1 ±1 and −15.5 ±2 kcal. per eq., respectively. The heat of neutralization of humic acid was −13.2 ±1 kcal. per eq. and that of Al‐saturated Mississippi bentonite was −5.5 kcal. per eq. The large difference in the heat of neutralization of the H‐ and Al‐saturated exchangers causes titration curves for the two to have widely differing slopes. This allows determination of the proportions of H and Al saturations of mixed H‐Al clays from the titration curves. The possible use of thermometric titrations in determining the course, mechanism and rate of a number of chemical reactions in soils is discussed and concluded to be excellent.