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Arsenic, Arsenic Trioxide, Arsenic Trichloride
I. Physical and Chemical Properties
A. Arsenic (metal).
1. Formula: As.
2. Appearance: Gray metal.
3. Melting point: Sublimes without melting at 613oC.
4. Specific Gravity: (H2O = 1): 5.73.
5. Solubility in water: Insoluble.
B. Arsenic Trioxide.
1. Formula: As2O3 (As4O6).
2. Appearance: White powder.
3. Melting point: 315oC.
4. Specific Gravity (H2O = 1): 3.74.
5. Solubility in water: 3.7 grams in 100cc of water at 20o C.
C. Arsenic Trichloride (liquid).
1. Formula: AsCl3.
2. Appearance: Colorless or pale yellow liquid.
3. Melting point: -8.5o C.
4. Boiling point: 130.2o C.
5. Specific Gravity (H2O = 1): 2.16 at 20o C.
6. Vapor pressure: 10mm Hg at 23.5o C.
7. Solubility in Water: Decomposes in water.
II. Fire, Explosion and Reactivity Data.
A. Fire: Arsenic, Arsenic Trioxide and Arsenic Trichloride are nonflammable.
1. Conditions Contributing to Instability: Heat.
2. Incompatibility: Hydrogen gas can react with inorganic arsenic to form the highly toxic gas arsine.
III. Monitoring and Measurement Procedures.
Samples collected should be full shift (at least 7-hour) samples. Sampling should be done using a personal sampling pump at a flow rate of 2 liters per minute. Samples should be collected on 0.8 micrometer pore size membrane filter (37mm diameter). Volatile arsenicals such as arsenic trichloride can be most easily collected in a midget bubbler filled with 15 ml of 0.1 N sodium hydroxide.
The method of sampling and analysis should have an accuracy of not less than plus or minus 25 percent (with a confidence limit of 95 percent) for 0.01 mg per cubic meter of air (10 mg/m3) and plus or minus 35 percent (with a confidence limit of 95 percent) for concentrations of inorganic arsenic between 0.005 and 0.01 mg/m3.