The alkali hydroxides are a class of chemical compounds which are composed of an alkali metal cation and the hydroxide anion (OH−). The alkali hydroxides are:
The most common alkali hydroxide is sodium hydroxide, which is readily available in most hardware stores in products such as a drain cleaner. Another common alkali hydroxide is potassium hydroxide. This is available as a solution used for cleaning terraces and other areas made out of wood.
All alkali hydroxides are very corrosive, being strongly alkaline.
A typical school demonstration demonstrates what happens when a piece of an alkali metal is introduced to a bowl of water. A vigorous reaction occurs, producing hydrogen gas and the specific alkali hydroxide. For example, if sodium is the alkali metal:
Sodium + water → sodium hydroxide + hydrogen gas2 Na + 2 H2O → 2 NaOH + H2