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(inorganic chemistry)
H3 As A colorless, highly poisonous gas with an unpleasant odor.



AsH3, a colorless, odorless gas (impurities usually produce an odor of garlic). Boiling point, —62.4°C; melting point, -113.5°C. Discovered in 1775 by K. W. Scheele. Pure arsine is produced by the action of water on sodium arsenide, Na3As. The reduction of acid-soluble arsenic compounds by hydrogen results in the formation of a mixture of arsine and hydrogen at the moment of liberation—for example:

As2O3 + 6Zn + 6H2SO4 = 2AsH3 + 6ZnSO4 + 3H2O

If the mixture is passed through a glass tube heated to 400°-500°C, the arsine will decompose into hydrogen and arsenic, which forms a black film with a vitreous luster along the cool sections of the tube. The test is used to determine the presence of arsenic in various substances; it was developed in 1836 by the English chemist J. Marsh (1794–1846).

Arsine is one of the most poisonous commercial toxins known. It generally induces acute poisoning. It has a primarily hemolytic effect. The latent period lasts two to eight hours, toward the end of which headache, dizziness, rigor, vomiting, and abdominal pain occur. The skin takes on a sunburned appearance, and body temperature initially rises to 38°-39°C. The patient may go into a coma after a certain period of time. Preventive measures against arsine poisoning include the use of arsenic-free metals and acids, the mechanization of production processes, the sealing of industrial equipment, and the creation of an effective ventilation system.