ISSN:
1420-9055
Keywords:
Enthalpies
;
dissolution kinetics
;
aqueous chemistry
;
surface chemistry
;
dissolution rates
;
minerals
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The pH-dependence of oxide dissolution rates is controlled by Brønsted acid-base reactions at the mineral surface. These reactions are rapid but depend explicitly on temperature, as do the subsequent slow rates of bond hydrolysis. The net result is that dissolution rates vary in a complicated fashion with temperature and solution pH. The enthalpy changes of acid-base reactions on oxide materials are sufficiently similar, however, that general statements can be made about their contribution. The enthalpy changes from proton adsorption to a hydroxyl functional group (▸SOH), or to a deprotonated functional group (▸SO −), are generally exothermic. The enthalpy changes become increasingly endothermic, however, as charge accumulates on the mineral surface and the charged species interact electrostatically. The result is that mineral dissolution rates are least sensitive to temperature, as measured with an Arrhenius-like rate law, at pH conditions near the Point of Zero Net Proton Charge.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00877275
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