Zinc Chloride is a chemical compound, composed of zinc and chlorine. It is a colourless liquid and it exhibits hygroscopic qualities, i.e., it attracts and captures the water molecule present in the environment. It is mildly corrosive towards metals. It is an ionic salt that is essential for the synthesis of protein, fats, and cholesterol, It may cause burns to the eyes, skin, and mucous membranes.
There are nine different crystalline forms of zinc chloride which are currently known. These hydrates of Zinc chloride are highly soluble in water.
Zinc Chloride Structure
A molecule of zinc chloride has an ionic bond between the zinc cation (Zn2+) and the chloride anions (Cl-).
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Physical Properties of Zinc Chloride
Zinc Chloride formula: ZnCl2.
Molecular Weight of Zinc Chloride: 136.315 gms/ mole
The boiling point of Zinc Chloride is - 732 °C
The Melting point of Zinc Chloride is - 290 °C
Its density is 2.907.
It forms white, odorless, very deliquescent granules.
Molten zinc chloride is viscous in nature and has a relatively low electrical conductivity.
Chemical Properties of Zinc Chloride
When ZnCl2 is dissolved in water, the solution becomes acidic. The pH of this aqueous solution of zinc chloride having a concentration equals 6M is approx 1.
After heating, the hydrated form of zinc chloride loses water and small quantities of ZnCl(OH) are obtained.
Zinc Chloride is soluble in water, glycerol, ether, and alcohol.
Zinc chloride is deliquescent in nature, so it should be protected from sources of moisture (water vapor).
Preparation of Zinc Chloride
The reaction between Zinc and hydrogen chloride gives an anhydrous form of zinc chloride. The chemical equation is given below:
Zn + 2HCl → ZnCl2 + H2
Hydrochloric acid reacts with zinc sulfide to form zinc chloride and hydrogen sulfide. The chemical equation is given by:
ZnS + 2HCl → ZnCl2 + H2S
There are some impurities present in zinc chloride samples due to the process of hydrolysis. The purification of chloride is simple due to its oxidation state Zn as +2. Purification can be done by recrystallization from hot dioxane. The purification of anhydrous zinc chloride can be done through sublimation with HCl gas, followed by the subsequent heating of the sublimate to around 400 °C with dry nitrogen gas. It can also be purified by treating it with thionyl chloride.
Uses of Zinc Chloride
Zinc Chloride finds its application in different industries including pharmaceuticals, health care, paper manufacturing industry. Chemical products are also made from zinc chloride.
Organic product synthesis - Organic products are synthesized in the laboratory for the preparation of Lewis acid reaction and various other organic reactions. It can be used as a catalyst in organic processes.
Metallurgical Industry - It is used as a flux in the soldering process and cleaning agent. It is also used in the manufacturing of magnesia cement.
Chemical industry - Zinc chloride finds its application in the manufacture of various dyes, intermediate chemicals, and solvents like ethyl acetate. It is found in antiseptic mouthwash products.
Printing and Textile industry - About 64% of zinc chloride in water can be used to dissolve silk, cellulose, and starch.
Petroleum - Zinc chloride is used as an emulsion breaker, which can separate oil from water.
Zinc chloride is used in dry cells as an electrolyte.
Other Uses - It is used as a condensing agent, disinfecting purposes, dehydrating agent, wood preservative, deodorant, and disinfectant.
A mixture of zinc oxide and hexachloroethane can be used in smoke grenades. While igniting, these compounds react with each other to form a smoke of zinc chloride, which serves as a smokescreen.
The Lucas reagent used is a solution of anhydrous zinc chloride and concentrated hydrochloric acid. This reagent is useful in preparing alkyl chlorides.
Zinc chloride is used as an alternative medicine for the cause of dead tissue, to cure skin cancers.
Zinc and Its Doses
Infants and Children: When taken by mouth properly in the prescribed quantities, zinc is likely Healthy. When used in high concentrations, zinc is Dangerous.
Pregnancy and Breast-Feeding: Zinc is likely safe when used in the prescribed daily quantities for most pregnant and breast-feeding women (RDA). Zinc, however, is potentially unsafe when used by breast-feeding women at high doses and likely unsafe when used by pregnant women at high doses. Not more than 40 mg of zinc should be taken per day by pregnant women over the age of 18, no more than 34 mg per day should be taken by pregnant women aged 14 to 18 years. No more than 40 mg of zinc per day should be taken by breastfeeding women over the age of 18, no more than 34 mg per day should be taken by breastfeeding women aged 14 to 18.
Alcoholism: Excessive, long-term consumption of alcohol is related to low absorption of zinc in the body.
Kidney Disease: The risk of having kidney disease rises with low zinc in the diet. People with hemodialysis kidney disease are also at risk for zinc deficiency and may need zinc supplements.
Vegetarianism: Vegetarian diets are often associated with lower absorption of zinc. This form of diet is also seen as a risk factor for the depletion of zinc. But in the long term, the body adapts. Zinc absorption and zinc loss elimination are getting stronger.