How is zinc chloride made and its properties.

How is zinc chloride made is a question that I get more often than "How does zinc chloride work?" and is the question on my mind as well. It's important to understand how it's actually made to add further understanding, in addition to consequences of the manufacturing process. Zinc chloride is produced by one of two methods.

1. Pyrolysis

This process begins by heating zinc oxide to a temperature between 600-800 degrees Celsius. The process works through the oxidation of zinc. It takes place at temperatures above 1000 degrees Celsius. At this temperature, zinc oxide converts to zinc chloride. The byproduct is carbon monoxide and carbon dioxide. This is one way that shows how is zinc chloride made.

2. Direct reaction

There's a direct reaction method that could be done through electrolysis of a cooled solution of zinc chloride in hydrochloric acid which can yield pure crystals of zinc chloride in large quantities. It's manufactured in the process byproducts called "waste". The waste byproduct are called polychlorinated dibenzofurans which is an organic compound present in the waste after the production of Zinc Chloride and also in Zinc Chloride itself that has toxicity and carcinogenity impacts on humans as well as animals.

Zinc chloride is highly effective reducing various types of sulfites; it is used to treat beer, wine and fruit juices. Zinc chloride is also used to control acidity changes in foods during processing. Food products that are sensitive to a change in acidity level can be protected from the effects by holding the pH level constant with a small amount of zinc chloride. It is also used as a food additive for its health benefits and color stability. It's a very common food additive especially in fermented products like sausages, pickles, and preserved meats. Though the compound has no taste or smell properties, it is odorless or with slight wrong odor due to its decomposition over time.

Properties of zinc chloride

1. It can be used as an antioxidant

The compound is an effective antioxidant, but this application was not practically applicable. As a result, it didn't get too much attention from the food-processing industry. Though zinc chloride has a low vapor pressure at room temperature or around 0.02 mmHg, it is non-volatile as well as it has no odor suggesting that most of its application will be in various types of foods emulsified with water such as butter and cheese where slight changes in pH might occur and lead to undesirable changes. The compound is very unstable at high temperatures, but even the product undergoes some degradation over time. When heated, it can undergo a series of reactions that result in formation of hydrochloric acid and zinc vapors.

2. It works as a catalyst for the preparation of chloroform, vinyl chloride and ethylene

The compound is an important component for the manufacture of chloroform, trichloroethylene and vinyl chloride. The application was not practically applicable, but it was studied in detail to determine its usefulness during production process.

3. It is a strong reducing agent: it react with Br to form HBr

This property is complementary to the fact that it's a reducing agent. A strong reducing agent is also a very strong electrophile, which has the ability to take electrons from other chemicals. As an example, hydrogen peroxide (H₂O₂) will react with zinc chloride (ZnCl₂) to produce Br and HBr in aqueous solutions.

4. It reacts with oxidizing agents

As a result of the reaction, ozone is formed along with hydrogen gas and water vapor. Hydrogen peroxide will react very rapidly with Zinc chloride forming Br and HBr gases, which are released from the solution. It should be noted that it will only react with these oxidizing agents and would not react with acids or strong alkalis.

5. It is a nucleophile: can be used to make Grignard reagent

With care, zinc chloride can be used for this purpose but it's only recommended for research settings due to the corrosive properties of Zinc Chloride. Zinc chloride is a common precursor to many Grignard reagents.

In conclusion, how is zinc chloride made is a question that many people want to know. It's important to understand because of the fact that one has to consider many risks like carcinogenetic and toxicity risks during the production process in addition to disposal of waste from the manufacturing process.