Chemical Properties
cubic crystals
Physical properties
White crystals; exists in three allotropic modifications: a rhombohedral gamma form that transforms to trigonal beta form at 75°C, the trigonal converting to a cubic alpha form at 145°C.
Density of the salt is 5.56 g/cm3; melts at 206°C; vaporizes at 450°C with decomposition; moderately soluble in water, 9.55 g/100mL at 20°C; insoluble in alcohol.
Uses
As a reagent in analytical chemistry, especially for the determination of iodine in presence of Br and Cl; also with KClO3, HgCl and resin for green fire for signalling at sea.
Preparation
Thallium nitrate is prepared by reacting thallium metal, thallous oxide, Tl2O or thallous hydroxide, TlOH, with nitric acid followed by crystallization: Tl
2O+ 2HNO
3 → 2TlNO
3 + H
2O TlOH + HNO
3 → TlNO
3 + H
2O.
General Description
A colorless crystalline solid melting at 206°C. Toxic by ingestion and skin absorption. Used to make other chemicals.
Air & Water Reactions
Water soluble.
Reactivity Profile
THALLIUM(I) NITRATE is an oxidizing agent. May start a fire when in contact with organic materials. Mixtures with alkyl esters may explode, owing to the formation of alkyl nitrates. Mixtures with phosphorus, tin(II) chloride, or other reducing agents may react explosively [Bretherick, 1979 p. 108-109].
Hazard
A poison. Strong oxidizing agent, fire and
explosion risk. TLV: 0.1 mg(Tl)/m3. Toxic by skin
absorption.
Health Hazard
Thallium is one of the more toxic elements both as an acute and a chronic poison. Effects of exposure are cumulative and onset of symptoms may be delayed 12 to 24 hours. May be fatal if inhaled, ingested or absorbed through the skin. Irritating to skin and eyes. Readily absorbed through the skin and digestive tract. Ingestion of soluble thallium compounds has caused many deaths Ingestion of sublethal quantities may cause nausea, vomiting, diarhea, abdominal pain, and bleeding from the gut accompanied or followed by drooping eyelids, crossed eyes, weakness, numbness, tingling of arms and legs, trembling, tightness and pain in the chest. Loss of hair may occur in two to three weeks. Severe intoxication may cause prostration, rapid heartbeat, convulsions, and psychosis. Some effects may be permanent.
Safety Profile
Poison by ingestion, intravenous, intraperitoneal, and subcutaneous routes. Human systemic effects by ingestion: hypermouhty, diarrhea, nausea or vomiting, and dehydration. Mutation data reported. When heated to decomposition it emits very toxic fumes of T1 and NO,. See also THALLIUM COMPOUNDS and NITRATES.
Carcinogenicity
There is inadequate carcinogenicity
data. From the results of a study with thallium sulfate
(383), the highest daily dose, 0.25 mg/kg, was
considered a NOAEL. Using the molecular weight of
TlNO3 to Tl for conversion, this NOAEL was
converted to 0.26 mg TlNO3/kg per day.
Purification Methods
The nitrate crystallises from warm water (1mL/g) on cooling to 0o. POISONOUS.
