<P> The pure anhydrous orthorhombic form (δ) rapidly changes to one of the other forms on exposure to the atmosphere, and a possible explanation is that the OH ions originating from the absorbed water facilitate the rearrangement . Rapid cooling of molten ZnCl gives a glass . </P> <P> The covalent character of the anhydrous material is indicated by its relatively low melting point of 275 ° C. Further evidence for covalency is provided by the high solubility of the dichloride in ethereal solvents, where it forms adducts with the formula ZnCl L, where L = ligand such as O (C H). In the gas phase, ZnCl molecules are linear with a bond length of 205 pm . </P> <P> Molten ZnCl has a high viscosity at its melting point and a comparatively low electrical conductivity, which increases markedly with temperature . A Raman scattering study of the melt indicated the presence of polymeric structures, and a neutron scattering study indicated the presence of tetrahedral (ZnCl) complexes . </P> <P> Five hydrates of zinc chloride are known: ZnCl (H O) with n = 1, 1.5, 2.5, 3 and 4 . The tetrahydrate ZnCl (H O) crystallizes from aqueous solutions of zinc chloride . </P>

How much chlorine will react with 5 grams of zinc to form zinc chloride