Acidic oxide Some non-metal oxides, such as nitrous oxide (NO) and carbon monoxide (CO), do not display any acid/base characteristics. Acidic oxides can also react with basic oxides to produce salts of oxoanions: Acidic oxides are environmentally relevant. Sulfur and nitrogen oxides are considered air pollutants as they react with atmospheric water vapour to produce acid rain. Although it is difficult to classify these oxides as acids, the property is manifest in reactions with bases. For example, carbon dioxide reacts with alkali. For this reason, alkali is kept in stoppered vessels to inhibit reaction with atmospheric carbon dioxide. In geochemistry complex silicates
Mixed oxides of nitrogen decreases the corrosiveness of the liquid, while the costs increase and the oxidation potential is decreased. The addition of nitric oxide also reduces the freezing point to a more desirable temperature. The freezing point of pure nitrogen tetroxide is , while MON3 is and MON25 is . Mixed oxides of nitrogen Mixed oxides of nitrogen (MON) are solutions of nitric oxide (NO) in dinitrogen tetroxide/nitrogen dioxide (NO and NO). It may be used as an oxidizing agent in rocket propulsion systems. A broad range of compositions is available, and can be denoted as MON"i", where "i" represents the percentage of