Zinc Chloride

About This Product

Zinc chloride, ZnCl2 with CAS number 7646-85-7, is a white crystalline solid, extremely hygroscopic and deliquescent, and among the most water-soluble salts known. It is also soluble in alcohols and in several organic solvents. Its classic application is soldering flux, and the mechanism explains why it works where milder fluxes do not. Solder will not wet a metal carrying an oxide film, and heating the joint makes that film grow faster. Zinc chloride hydrolyses in the presence of moisture to release hydrochloric acid at soldering temperature, which strips the oxide from the surface just as the solder flows, and the molten salt then forms a protective blanket that stops the metal reoxidising before the joint is made. The same aggressiveness means flux residue must be washed off, since it will corrode the joint it just made. Elsewhere it is used as a Lewis acid catalyst in organic synthesis, notably in Friedel-Crafts and Lucas reagent chemistry, as a wood preservative and fire retardant, as a dehydrating and condensing agent in textile and paper processing, and as the electrolyte in zinc-carbon dry cells. It is used in soldering and galvanising fluxes, organic synthesis catalysis, wood preservation, textile mercerising, dry cell batteries and vulcanised fibre manufacture. Bio Green Chem supplies zinc chloride to specification on assay, basic salt, ammonium, iron, lead, sulfate and insolubles.