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Calcium hydride (CaH2) is a powdered chemical compound with a salt-like crystal structure. In its pure form it is white, but is more commonly found in a less pure form with a gray shading. The chemical compound is made by combining calcium and hydrogen at high temperatures. It sees use in several industrial applications including the production of hydrogen, use as a desiccant chemical, and in the creation of certain metals via the Hydromet process.
The chemical compound CaH2 is sometimes used to produce pure hydrogen in laboratory settings. In the 1940s, calcium hydride was marketed under the name Hydrolith and was promoted as a method to create hydrogen for inflating weather balloons and dirigibles. Due to the immense quantities of calcium hydride needed to inflate air ships, however, it was not considered to be a cost-effective means of inflating dirigibles and other large air ships.
Due to its composition, the chemical is also used as a reducing and drying agent for some solvents. The use of mild desiccants as a pre-drying solution is preferable in some industrial applications to avoid dangerous chemical interactions. Calcium hydride can be used as such a pre-drying agent to remove many solvents before using more aggressive desiccants. By using the milder desiccant to remove solvents prior to applying more aggressive chemicals, volatile chemical reactions can be prevented.
Using the Hydromet process, this compound is also used to create certain metals. These include titanium, chromium, and zirconium. The metals created in this process are used in a number of industrial and manufacturing applications.
There are several issues that should be addressed when using calcium hydride for industrial applications. The hydrogen produced by calcium hydride is extremely flammable, posing dangers for explosion and fire. When used as a desiccant, this chemical compound reacts slowly with many solvents, which translates to increased drying times. In other cases, the chemical compound reacts violently with solvents, particularly chlorocarbons, creating possible hazards.
Aside from these considerations, the chemical compound is also subject to other issues when used as a desiccant in industrial settings. Calcium hydride (CaH2) is visually indistinguishable from Ca(OH)2 making misidentification possible. This compound will not remove dissolved oxygen from solvents.
The use of CaH2 requires special protective gear for safe handling. As an industrial drying agent, this compound is considered to be a desiccant and reducing agent of choice in many applications. When the chemical is used properly, it is considered to be safe for use.