Here are the important points. Aluminum is very reactive with oxygen, more so than even hydrogen. So, in the presence of water, it will take the oxygen from the hydrogen, thus freeing. However, the aluminum oxide that is left is extremely non-reactive and insoluble. In a crystalline form, aluminum oxide is known as sapphire or ruby, depending on the color. My guess is that in gallium, both aluminum and aluminum oxide are soluble. So, instead of being left behind on the surface of the aluminum, thus limiting the reactions that can occur, the aluminum is made available for more reactions.
Gallium has a pretty low melting point, about 30 degrees C or 86 degrees F. Now, I am not an expert on the element, but from the articles, it readily dissolves aluminum, forming an amalgam. Like mercury does with many metals like silver and gold. So the gallium could be loaded up with aluminum pretty easily. When water is introduced, the aluminum at the surface would react, forming the hydrogen and aluminum oxide. Enough heat should be generated to keep the amalgam in a liquid state, if, in fact, it was cool enough the be a solid in the first place. Not a given in our part of the country. Anyway, the gallium and the aluminum oxide could later be separated by distillation, if nothing else. So dealing with it is very low tech. and easy. |
