SODIUM THIOSULPHATE (Na₂S₂O₃)

SYNONYMS
Thiosulphuric acid, sodium hyposulphite, hypo.
GENERAL PRECAUTIONS
Avoid ingestion.
Keep away from heat.
Keep away from acids and strong oxidisers.
Keep the container tightly closed.
Wash hands thoroughly after handling.
CHARACTERISTICS
Colourless crystals.
HEALTH HAZARD DATA
Sodium thiosulphate is moderately toxic when ingested.
TREATMENTS
Skin ­ immediately remove contaminated clothing and wash the affected area with soap or mild detergent and large amounts of water until all evidence of the chemical has been removed (approximately 15 minutes). Wash contaminated clothing before re­use.
Eyes ­ immediately wash the affected eye with large amounts of water until all evidence of the chemical has been removed (approximately 15 minutes). If irritation or pain persist seek medical attention.
Inhalation ­ remove from the area of exposure to fresh air. If breathing has ceased apply artificial respiration. Keep warm and allow to rest. If irritation persists or develops seek medical attention.
Ingestion ­ wash out the mouth thoroughly with water and give water to drink. Induce vomiting by touching a finger to the back of the throat. Seek immediate medical advice.
INCOMPATIBILITY
Sodium thiosulphate is incompatible with iodine, acids, lead, mercury, silver salts and oxidising agents. A violent reaction occurs when mixed with sodium nitrite. Heating produces toxic fumes of sulphur compounds.
STORAGE
Store in a cool, dry atmosphere away from heat and incompatible substances.
HANDLING
Wear protective clothing. A long sleeved laboratory coat or gown, rubber gloves, safety goggles and a face mask as a minimum standard.
DISPOSAL
WEAR:
Rubber gloves, safety glasses and laboratory coat. Work in a fume hood or wear a respirator.
SPILLS:
Gas leak: eliminate all sources of ignition. If the valve is leaking because it cannot be closed, the gas can be bubbled through a calcium hypochlorite solution. Be sure to include a trap in the line to prevent the solution being sucked back into the cylinder.
Solid: cover the spill with soda ash or sodium bicarbonate. Mix and spray with water. If effervescent wait until the reaction is complete. Scoop into a large beaker and cautiously add an equal volume of calcium hypochlorite (the reaction may be vigorous). Add more water, stir and allow to stand for one hour. Dilute and neutralise the oxidised solution and discharge to sewer with a large excess of water.
PACKAGE LOTS:
If a gas, bubble into a soda ash solution. if a solid, mix with an equal volume of soda and water to form a slurry, use a large container. In either case add calcium hypochlorite. Add more water if necessary and allow to stand for two hours. Neutralise the oxidised solution then discharge to the sewer with a large excess of water.
ENVIRONMENT:

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