Zinc battery plate electrodes are analyzed for zinc oxide, zinc chloride, zinc fluoride, zinc carbonate, zinc oxychloride, total zinc, zinc as the metal, and trace metals. A variety of methods are used to determine each of these components. The amount of zinc in each of the zinc compounds is determined by multiplying the percent of the compound by the ratio of the molecular weights of zinc to the zinc compound. This percent zinc is subtracted from percent total zinc and the operation is performed for every zinc compound determined. The remaining zinc value after these subtractions represents zinc as the metal. Zinc metal is the charged state on the anode. Percent total zinc is required in all these calculations. The importance of these components cannot be overemphasized. The presence, or absence, of certain components in the zinc electrode can influence its behavior in a zinc-silver oxide primary battery. Passivation layers, tendency to dendritic growth, corrosion rates, voltage rise times, current density, porosity, surface area, electrochemical capacity, and other considerations make it imperative that the chemical composition of the zinc electrode be known. The focus of this project was to evaluate the existing method for total zinc and to develop a better method. The existing method uses the disodium salt of ethylenediamine tetraacetic acid (EDTA) with Eriochrome Black T as the indicator.
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