A compound formed by reaction of lead oxides (or hydroxides) with alkali. The oxides of lead are amphoteric (weakly acidic) and react to give plumbate ions. With the lead(IV) oxide, reaction with molten alkali gives the plumbate(IV) ion PbO2+2OH− → PbO32−+H2O In fact, various ions are present in which the lead is bound to hydroxide groups, the principal one being the hexahydroxoplumbate(IV) ion Pb(OH)62−. This is the negative ion present in crystalline ‘trihydrates’ of the type K2PbO3.3H2O. Lead(II) oxide gives the trihydroxoplumbate(II) ion in alkaline solutions PbO(s)+OH−(aq)+H2O(l) → Pb(OH)32−(aq) Plumbate(IV) compounds were formerly referred to as orthoplumbates (PbO44−) or metaplumbates (PbO32−). Plumbate(II) compounds were called plumbites.
PbO2+2OH− → PbO32−+H2O
PbO(s)+OH−(aq)+H2O(l) → Pb(OH)32−(aq)