ABSTRACT
Divalent oxides include a series of compounds that have been the subject of much work: alkaline earth oxides, transition metal oxides, and Group 12. This chapter gives a list with references (noncomprehensive) to dissolution studies. Some typical rate data, expressed as penetration rates, are also given, although they should be taken only as indicative. The rate data refer to dissolution in mineral acids at room temperature and aH+ = 0.1. The rate of dissolution of CaO is not decreased by interfacial reactions; it is controlied by diffusion of reagents and/or products in the aqueous phase. It may be inferred that the same applies for the oxides of the heavier congeners, SrO and BaO. The interfacial reactions are however slower for MgO and much more so for BeO. The most important nickel oxide is Ni1-xO, in which the oxidation state of Ni is predominantly 2+.
