Preparation and Purification
Anhydrous ZnCl2 can be prepared from zinc and hydrogen chloride.
- Zn + 2 HCl → ZnCl2 + H2
Hydrated forms and aqueous solutions may be readily prepared similarly by treating Zn metal with hydrochloric acid. Zinc oxide and zinc sulfide react with HCl:
- ZnS(s) + 2 HCl(aq) → ZnCl2(aq) + H2S(g)
Unlike many other elements, zinc essentially exists in only one oxidation state, 2+, which simplifies purification of the chloride.
Commercial samples of zinc chloride typically contain water and products from hydrolysis as impurities. Such samples may be purified by recrystallization from hot dioxane . Anhydrous samples can be purified by sublimation in a stream of hydrogen chloride gas, followed by heating the sublimate to 400 °C in a stream of dry nitrogen gas. Finally, the simplest method relies on treating the zinc chloride with thionyl chloride.
Read more about this topic: Zinc Chloride
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