ARSENIC ACID Chemical Properties

Melting point:

35.5℃ [HAW93]

Boiling point:

160℃[at 101 325 Pa]

Density 

2.5 [CRC10]

vapor pressure 

18.45hPa at 25℃

solubility 

very soluble in H2O, ethanol

form 

exists only in solution

pka

3.09±0.10(Predicted)

color 

exists only in solution

PH

pKa1= 2.31, pKa2 = 7.05, pKa3 = 11.9(25℃)

Water Solubility 

very soluble H2O, EtOH [CRC10]

Stability:

Incompatible with metals.

CAS DataBase Reference

7778-39-4(CAS DataBase Reference)

EPA Substance Registry System

Arsenic acid (7778-39-4)

Safety Information

RIDADR 

1554

HazardClass 

6.1(a)

PackingGroup 

II

Hazardous Substances Data

7778-39-4(Hazardous Substances Data)

MSDS

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ARSENIC ACID Usage And Synthesis

Chemical Properties

Arsenic acid is a clear, white, semi-transparent crystal (sugar or sand-like) material. Arsenic acid is one of the most commercially important pentavalent compounds of arsenic. It is used for wood treatment/wood preservative, as a drying agent, a soil sterilant, and to make other arsenates. It is a broad-spectrum biocide, a fi nishing agent for glass and metal, and a reagent in the retard of dyestuffs and organic arsenic compounds. Arsenic acid decomposes on heating, producing toxic and corrosive fumes. It is a strong oxidant and reacts with combustible and reducing materials and attacks/ damages metals to produce toxic and flammable arsine. It is soluble in water and forms the arsenate ion.

Chemical Properties

White, translucent crystals. Soluble in water, alcohol, alkali, glycerol.

Physical properties

Hygroscopic translucent crystals; density between 2 to 2.5 g/cm³; melts at 35.5°C; loses water when heated to 160°C; highly soluble in cold water; soluble in alcohol, glycerol and alkalies.

Uses

Pesticides; herbicides; fungicides; algicides.

Preparation

Arsenic acid is prepared by treating arsenic trioxide with concentrated nitric acid; or by combination of arsenic pentoxide with water. The latter reaction is very slow. It is also formed when meta- or pyroarsenic acid is treated with cold water.

Definition

Any salt or ester of arsenic acid. They are distributed widely in nature and contaminate coal and metal ores. Arsenates uncouple oxidative phosphorylation by replacing inorganic phosphorous in the ATP.

General Description

White crystals. Melting point 95°F. Excessive drying produces As2O5.5/3H2O.

Air & Water Reactions

Hygroscopic. Water soluble.

Reactivity Profile

ARSENIC ACID may evolve very toxic gaseous arsine (AsH3) from contact with active metals, such as zinc and aluminum [Inorganic Chemicals Handbook, I, p. 175]. When heated to decomposition, ARSENIC ACID produces toxic fumes of metallic arsenic [Sax, 9th ed., p. 271]. The solution is weakly acidic and a weak oxidizing agent. Reacts with alkalis to generate some heat and precipitate arsenates.

Hazard

Carcinogen; toxic.

Health Hazard

Ingestion cuases irritation of stomach, weakness, other gastrointestinal symptoms. Overdose can cause arsenic poisoning, but symptoms are delayed.

Health Hazard

Arsenic acid is absorbed into the body by inhalation of its vapor, through the skin, and by ingestion. Arsenic acid is an eye irritant and may cause burns. Most injuries result from exposure to dusts, causing conjunctivitis, lacrimation, photophobia, and chemosis. Exposures to arsenic acid cause poisoning with symptoms of irritation of the eyes, the skin, the respiratory tract, respiratory distress, sore throat, nausea, vomiting, diarrhea, poor appetite, and stomach cramps. Arsenic acid also causes effects on the blood, cardiovascular system, gastrointestinal tract, liver, and peripheral nervous system, leading to polyneuropathy and convulsions. Repeated exposures to high concentrations of arsenic acid have been reported to cause nerve damage, with “pins and needles,” numbness, and weakness of the arms and legs, and even death. Tachycardia is frequently reported following ingestion of arsenic acid salts and is contributed to by anxiety, intravascular fl uid depletion, and possibly direct arsenic-induced cardiotoxicity.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Safety Profile

Confirmed human carcinogen. Poison by ingestion. An experimental teratogen. Human mutation data reported. When heated to decomposition it emits toxic fumes of arsenic. See also ARSENIC COMPOUNDS.

storage

Arsenic acid should be kept stored in an area without drain or sewer access. It should be separated from strong oxidants, strong bases, metals, strong reducing agents, food, and feedstuffs. Occupational workers should keep arsenic acid in a cool, well-ventilated area, away from heat. Workers should avoid storing or transporting arsenic acid with aluminium, copper, iron, or zinc.

Precautions

Occupational workers should be extremely careful and cautious during handling and use of arsenic acid.

ARSENIC ACID(7778-39-4)Related Product Information

• Silver arsenate(III)
• DIAMMONIUM ARSENATE,AMMONIUM ARSENATE (ORTHO),AMMONIUM ARSENATE TRIBASIC,AMMONIUM ARSENATE (DI),AMMONIUM ARSENATE
• IRON(II)ARSENATE(3:2),FERROUS ARSENATE
• CALCIUM ARSENATE,Calcium arsenate, min. 95%
• lead arsenate (1:1)
• Silver arsenate(V)
• BARIUM ARSENATE
• AMMONIUM ARSENATE MONOBASIC,AMMONIUM DIHYDROGEN ARSENATE
• Lead(II) arsenate(III)
• CESIUM DIHYDROGEN ARSENATE
• Arsenic acid potassium salt, Potassium dihydrogen arsenate
• COPPER (II) ARSENATE,CUPRIC ARSENATE
• ANTIMONY ARSENATE
• SODIUM ARSENATE, HEPTAHYDRATE
• Ferric arsenate
• BISMUTH ARSENATE
• CADMIUM ARSENATE
• COBALTOUS ARSENATE,COBALT ARSENATE