Arsenic hydride, decomposition

Tests by reduction to arsenic hydride and decomposition with silver nitrate or gold chloride ... 

The hydrides of phosphorus, arsenic, and antimony thus form an interesting transition series. On similar sorts of surface antimony hydride is the least stable, decomposing with measurable speed at ordinary temperatures, and phosphine is the most stable, not decomposing at an appreciable rate below a red heat. Arsine occupies an intermediate position. At low temperatures the adsorption is considerable, and, as a result, the stibine decomposition requires the pn equation, while the more stable hydrides, which only decompose rapidly at higher temperatures where the adsorption is smaller, obey the unimolecular law. It is interesting, moreover, that with stibine itself the exponent n increases towards unity as the temperature at which the reaction takes place is raised. 

B. Welz, M. Melcher, Decomposition of marine biological tissues for determination of arsenic, selenium and mercury using hydride-generation and cold vapour atomic absorption spectrometeries, Anal. Chem., 57 (1985), 427-431. 

The hydrides of the heavier members of Group VA are easily decomposed. For example, the decomposition of arsine serves as a basis for the Marsh test for arsenic in which an arsenic mirror forms when arsine is passed through a heated tube ... 

NIOSH REL (Arsine) CL 2 ng(As)/mVl5M DOT CLASSIFICATION 2.3 Label Poison Gas, Flammable Gas SAFETY PROFILE Confirmed human carcinogen. Poison by inhalation. Human red blood cell, gastrointestinal system, central nervous system, and other systemic effects by inhalation. Flammable when exposed to flame. Moderately explosive when exposed to CI2, HNO3, (K + NH3), open flame, or powerful shock. Dangerous, more toxic than its oxidation product. When heated to decomposition it emits highly toxic fumes of arsenic. See also ARSENIC, ARSENIC COMPOUNDS, and HYDRIDES. 

SAFETY PROFILE Poison by ingestion and intraperitoneal routes. A trace mineral added to animal feeds. Potentially explosive reaction with charcoal + ozone, metals (e.g., powdered aluminum, copper), arsenic carbon, phosphoms, sulfur, alkali metal hydrides, alkaline earth metal hydrides, antimony sulfide, arsenic sulfide, copper sulfide, tin sulfide, metal cyanides, metal thiocyanates, manganese dioxide, phosphorus. Violent reaction with organic matter. When heated to decomposition it emits very toxic fumes of I and K2O. See also lODATES. 

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