Environmental Impacts of Base Anhydrides

As discussed here, metal oxides such as \(CaO\) form basic solutions when mixed into water. Since most metal oxides have relatively low solubility, this is not as important as the environmental impacts of acid anhydrides, but it is worth understanding. 

The most common base anhydride (at least in normal life) is lime, CaO. This compound is called lime since it is derived from limestone (\(CaCO_3\)) through decomposition:

\(CaCO_3 \rightarrrow CO_2 + CaO\)

Lime has a number of industrial uses, but the use you are most likely to come in contact with is the production of cement and concrete. Lime is a major component of these. (Don't get confused. Cement is not lime just like cookies are not flour. Lime is an ingredient in cement.)

The inclusion of lime in cement is one of the reasons that working with cement can cause skin trouble for workers and why the recommendation is to wear gloves when working with wet cement. 

Additionally, soil in contact with cement will be slightly more basic than soil further away. That means that acid-loving plants, such as azaleas will do better planted away from the foundation of your house than right up against it. 

On the other side of the situation, some soils are naturally acidic which can, in some cases, inhibit grass from growing well. In those cases, adding lime to the soil can bring the pH up to a healthier level.