ABSTRACT
Zinc is an active metal above hydrogen in the electromotive force cale. It normally liberates hydrogen when immersed in aqueous solution. It also has a high hydrogen overpotential depending somewhat on pH. This kinetically hinders the hydrogen evolution reaction and renders zinc fairly stable in aqueous solutions. Because of the high hydrogen overpotential, the zinc ion can be reduced to metal, permitting quantitative determination of zinc by cathodic deposition. The analytical estimation is more favorable at high pH when the zincate or complex cyanide is the predominant solution species. The zinc ion is expected to form sp3 hybridized orbitals with sigma covalent bond formation to give tetrahedral coordinated ions in solution. Complex ion formation generally follows the pattern of successive addition of the complexing ion, probably displacing water to form the zinc complex. Oxidation states higher that +2 are unknown except for the gaseous phase.
