Crystallise it from aqueous EtOH or dilute H2SO4 below 39o when it forms the heptahydrate, and between 39o and 70o it forms the hexahydrate, and above 70o the monohydrate is stable. The anhydrous salt is obtained from the hydrates by heating at 280o or lower temperatures in a current of dry air. It decomposes to ZnO and SO2 at 767o. The solubility of the heptahydrate in H2O is 5.88% at 0o, 61.92% at 30o, 66.61% at 35o and 70.05% at 39o.
Acidic salts, such as Zinc sulphate, are generally soluble in water. The resulting solutions contain moderate concentrations of hydrogen ions and have pH's of less than 7.0. They react as acids to neutralize bases. These neutralizations generate heat, but less or far less than is generated by neutralization of inorganic acids, inorganic oxoacids, and carboxylic acid. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible. Many of these compounds catalyze organic reactions.
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.
ChEBI: A metal sulfate compound having zinc(2+) as the counterion.
Zinc sulfate occurs in nature as the mineral, zinkosite. The heptahydrate, ZnSO4•7H2O is the mineral, goslarite. The salt is used as a mordant in calico-printing, in making rayon, in preserving wood, in animal feeds, in electroplating, and in preparing many zinc compounds.
Anhydrous Zinc sulphate is a colorless crystalline solid. Zinc sulphate is also obtained as a hexahydrate, ZnSO4.6H2O, and as a heptahydrate ZnSO4.7H2O. All forms are soluble in water. All are noncombustible. The primary hazard is the threat posed to the environment. Immediate steps should be taken to limit its spread to the environment. Zinc sulphate is used in the production of rayon, as a feed supplement, used to obtaine lectrolyte zinc, in printing textiles and to make lithopone, to impregnate wood and hides,as an additive to spinning baths for production of synthetic silks, in electroplating, and in animal feeds.
Inhalation of dust causes irritation of nose and throat. Ingestion can cause irritation or corrosion of the alimentary tract. Contact with eyes or skin causes irritation.
Zinc sulfate is produced as an intermediate in recovering zinc from mineral zinc blende, ZnS (see Zinc, Recovery). The mineral is roasted at about 1,000°C to form zinc oxide and sulfur dioxide which, on prolonged heating in excess air, converts to zinc sulfate:
2ZnS + 3O2 → 2ZnO + 2SO2
992 ZINC SULFATE2ZnO + 2SO2 + O2 → 2ZnSO4
In the zinc recovery process, roasted products are leached with sulfuric acid, whereupon zinc oxide is converted to sulfate.
ZnO + H2SO4 → ZnSO4 + H2O
Also, zinc sulfate can be prepared by reacting metallic zinc with dilute sulfuric acid followed by evaporation and crystallization:
Zn + H2SO4 → ZnSO4 + H2
Air & Water Reactions
Water soluble. Efflorescent in air. Aqueous solutions are acidic.
- Convergence preservatives: as eye drops, can be used for the treatment of conjunctivitis, trachoma, nasal blepharitis and so on.
- Oral stimulation of gastric mucosa can cause reflex vomiting. It can be used as emetic drug, now less used.
- It can be used for the treatment of zinc deficiency: zinc is the ingredient of many important enzymes in vivo such as carbonic anhydrase and alkaline phosphatase, being an indispensable trace element in the human body. Supplementation of zinc can be used for treating zinc deficiency such as dwarfism, acral dermatitis and zinc deficiency caused by long-term vein nutritional deficiency and so on.
- It can be used for the treatment of zinc deficiency related diseases: such as acne vulgaris, skin ulcers (venous, arterial, leprosy), psoriasis, seborrheic dermatitis, chronic eczema, oral ulcers, hair loss and smell taste disorders.
- It can be used as mordant for printing and dyeing, wood preservative, bleaching agent for papermaking, also used in medicine, artificial fiber, electrolysis, electroplating, and pesticide as well as zinc salt production.