Alkali metal hydroxide

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:

The alkali metal hydroxides are the strongest of all bases.The order of basicity increases down the group, i.e., LiOH is the least basic and CsOH, the most basic hydroxide. It is due to the property of bases to donate OH−
ion and due to small size and high lattice enthalpy of Li, it donates less OH−
and large size and low lattice enthalpy of Cs, Cesium hydroxide donates more OH−
ions than any other hydroxide. All the alkali metal hydroxides are white crystalline solids and dissolve freely in water with evolution of much heat.

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