The nature of acidic and basic (alkaline) oxides can be easily illustrated via a series of three straightforward classroom demonstrations for high school and general chemistry courses. Properties of carbon dioxide, sulfur dioxide, and magnesium oxide are revealed inexpensively and safely. Additionally, the very different kinetics of hydration of SO[subscript 2] (rapid) and CO[subscript 2] (slow) are evident. The pH changes observed by use of universal indicator provide striking visual evidence that makes the concepts of acidic and basic oxides less abstract and more concrete than verbal or written descriptions alone. By using the MgO solution for the SO[subscript 2] hydration reaction, one can mimic environmental interactions that lead to the neutralization of alkaline and acidic species. Interestingly, the SO[subscript 2] and CO[subscript 2] demonstrations can easily be adapted to environmental chemistry courses and especially the very relevant realm of climate change science. The difference in hydration rates explains why CO[subscript 2] is a greenhouse gas, but SO[subscript 2] is not listed as one. Variations of the CO[subscript 2] hydration demonstration reveal the sensitivity of oceans to acidification by dissolved CO[subscript 2] and the relationship of fossil fuel combustion to ocean acidification.