Sodium thiosulfate crystal

CAS №

7772-98-7

ГОСТ

GOST 244-76

Формула

Na2S2O3 • 5H2O

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Description

Application

Crystalline sodium thiosulfate is for photography, film industry, leather, fur, pulp and paper, chemical and other industries.

Safety requirements

Sodium thiosulfate fire and explosion proof. The dust is toxic.

Packing

Sodium thiosulfate is packed in four-, five-, six-layer paper bags or plastic bags, liners, enclosed in paper bags or flax, jute bags kenafnye or wooden barrels with a capacity of up to 100 dm³. Sodium thiosulfate is also packaged in a special soft disposable containers.

Guaranteed shelf life

1 year from date of manufacture.

Physical and chemical properties

Item	Norm
	Photocal	Technical
	Photocal	Top	First
Appearance	Non-caking colorless crystals or granules, may be off-white, yellow, pink.
Mass fraction of sodium thiosulfate in terms of Na₂S₂O₃•5H₂O, %, not less	99.0	98.5	98.0
Total iron (Fe^{2 +}), %, not more	0.001	0.002	0.003
Insoluble in water, %, not more	0.01	0.03	0.03
Mass fraction of sodium sulfide (Na₂S), %, not more	0.001	0.001	0.001
Calcium, magnesium, and substances that are not soluble in the ammonium solution, %, not more	0.02	—	—
Heavy metals (Pb^{2 +}), %, not more	0.001	—	—
pH of the aqueous solution at 20 °C	6.5–9.5	—	—
Appearance of an aqueous solution	Colorless, transparent	—	—

Safety requirements

Class of danger	—
Basic properties and hazards
Basic properties	Non-caking colorless crystals or granules, may be off-white, yellow, pink. Non-volatile, soluble in water. Water and acids can decompose to form toxic and flammable gases. Corrosive. Pollutes water.
Explosion and fire	Fire-and explosion-proof. Fire resistant. Upon contact with the flame, forms toxic gases (sulfur oxides, etc.).
The risk to humans	Can kill is ingested! Harmful by inhalation and if swallowed (a burning sensation in the mouth, nose and throat, metallic taste, nausea, vomiting, weakness, in severe cases of poisoning — gasp, fainting, seizures), in contact with skin (redness, dryness, itching) and in the eyes (слезотечие, pain in the eyes.) Possible chemical burn. The dust is toxic. When injected into the human body, it can cause vomiting, lethargy, circulatory disorders, heart palpitations. Under the action of acid, sodium thiosulfate decomposes with the release of sulfur dioxide (4th class of danger). Sulfur dioxide (SO 2) — a colorless gas with a pungent odor, irritating to mucous membranes. Prolonged exposure causes acute inflammation of the mucous membranes and bronchial (cough, sore throat and chest, tearing).
Individual protection means	RC-3 (for 20 minutes). Insulating protective clothing FIR 5 complete with an insulating mask IP-4M. Special clothing, respirator type Y-2K, SB-1 "Petal".