Hydroxides of Group 1 metals

In 2002, ≈45Mt of NaOH (caustic soda) were used worldwide, with about one-third of this total being manufactured in the US. NaOH is used throughout organic and inorganic chemistry wherever a cheap alkali is needed. Solid NaOH (mp 591 K) is often handled as flakes or pellets, and dissolves in water with considerable evolution of heat. Potassium hydroxide (mp 633 K) closely resembles NaOH in preparation and properties. It is more soluble than NaOH in EtOH, in which it produces a low concentration of ethoxide ions this gives rise to the use of ethanolic KOH in organic synthesis.

The crystal structures of the group 1 hydroxides are usually complicated, but the high-temperature form of KOH has the NaCl lattice, with the [OH]^- ions undergoing rotation rendering them pseudo-spherical. The reactions of alkali metal hydroxides with acids and acidic oxides call for no special mention.

Many non-metals disproportionate when treated with aqueous alkali: P₄ gives PH₃ and [H₂PO₂]^-, S₈ gives S^2- and a mixture of oxoanions, and Cl₂ reacts to give Cl^- and [OCl]^- or [ClO₃]^-. Non-metals that do not form stable hydrides, and amphoteric metals, react with aqueous MOH to yield H₂ and oxoanions.