Sorry if this is a dumb question but I'm an ME and am only now starting to get a grip on chemistry. If I have ruby (Cr:Al2O3) in a humidified air environment that contains KOH, my limited chemistry knowledge tells me that the alkali, KOH, will react with the ruby. However, I can't figure out what the products of this reaction are. Since there is no hydrogen in the alumina, it can't be a acid-base reaction. So, I'm going to guess its a double placement reaction. Based on this, I get the following unbalanced reaction; KOH + Cr:Al2O3 -> K2O + Al(OH)3 + Cr(OH)3 However, this just doesn't seem right to me as K2O is a rather unstable compound. Am I doing this right? Any help would be much appreciated.