Zinc sulfate appears as colorless or white rhombic crystals or powder at room temperature. It has convergence property and is easily soluble in water with its aqueous solution being acidic. It is slightly soluble in ethanol and glycerol. Pure zinc sulfate can be stored in the air for a long time without turning yellow. It can lose water to become white powder when placed in dry air. There are various kinds of hydrates: in the range of 0-39 ° C, its stable hydrate balanced with aqueous phase is zinc sulfate heptahydrate; in the range of 39-60 ° C, it is hexahydrate zinc sulfate. At the range of 60-100 °C, it will become zinc sulfate monohydrate. When being heated to 280 °C, various kinds of hydrate will completely lose water with decomposition into zinc sulfate at 680 °C and further decomposition at above 750 ° C and finally decomposition into zinc oxide and sulfur trioxide at about 930 °C. ZnSO4 • 7H2O can form mixed crystal with MSO4 • 7H2O (M = Mg, Fe, Mn, Co, Ni) within a certain range. It is mainly used for the preparation of raw materials of pigment lithopone, zinc barium and other zinc compounds. It also has various kinds of applications such as animal nutrition upon zinc deficiency, animal feed additives, crop zinc fertilizer (trace element fertilizer), important materials of artificial fiber, electrolyte solution upon electrolytic production of zinc metal, mordant in the textile industry, pharmaceutical emetic agents, astringents, fungicides and wood and leather preservatives. It can be derived from the reaction between zinc or zinc oxide and sulfuric acid or from the baking of sphalerite in the baking furnace followed by extraction and refining.
