THE THERMAL-DECOMPOSITION OF AMMONIUM-CHLORIDE TETRACHLOROZINCATE AND THE FORMATION OF TETRACHLOROZINCATE COMPLEXES OF ALKALI-METAL BY MEANS OF SOLID REACTIONS WITH ALKALI CHLORIDES

Ammonium chloride tetrachlorozincate, (NH//4)//3Cl left bracket ZnCl left bracket 4 right bracket , decomposes to ZnCl//2 in two stages through an intermediate phase (NH//4)//2 left bracket ZnCl//4 right bracket . In the first stage, 1 mol of NH//4Cl is lost by one-dimensional diffusion mechanisms with the activation energy of 138 kJ mol** minus **1, and in the second stage the release of two moles of NH//4Cl is controlled by a random nucleation reaction with the activation energy of 126 kJ mol** minus **1, corresponding to the bond-breaking. Anhydrous alkali metal tetrachlorozincate complexes, M//2 left bracket ZnCl//4 right bracket (M equals Na, K, Rb, Cs), are obtained by solid reactions with alkali chlorides when (NH//4)//3Cl left bracket ZnCl//4 right bracket decomposes.