What form is Sodium Thiosulfate CAS 7772-98-7 supplied in?

Commercial sodium thiosulfate is commonly supplied as sodium thiosulfate pentahydrate, Na₂S₂O₃·5H₂O. The page uses CAS 7772-98-7, while some databases assign the pentahydrate CAS 10102-17-7, so confirm the physical form and water of crystallization before ordering.

How is sodium thiosulfate different from sodium sulfite?

Sodium thiosulfate contains the thiosulfate ion S₂O₃²⁻, while sodium sulfite contains SO₃²⁻. The additional sulfur changes its reducing, metal-complexing, and photographic-fixing behavior.

How is Sodium Thiosulfate used for dechlorination?

Sodium thiosulfate reacts with residual free chlorine and chloramines in water, wastewater, and aquaculture systems to form less harmful species. The required dose should be calculated from the measured chlorine residual and checked by testing to avoid overdosing.

What are the main industrial applications of Sodium Thiosulfate?

Sodium thiosulfate is used for dechlorination, as a photographic fixing agent, in textile and paper processing including sulfur dyeing, and as a reducing, neutralizing, or complexing agent. It is also used in iodometric titration and some metal recovery processes.

What specifications should be checked for Sodium Thiosulfate CAS 7772-98-7?

Confirm assay, appearance, water of crystallization, pH, chloride, sulfate, iron, heavy metals, and insoluble matter. Also specify the intended technical, photographic, or water-treatment grade and whether granules or powder are required.

Sodium Thiosulfate CAS 7772-98-7

Sodium Thiosulfate (sodium hyposulfite), CAS 7772-98-7, is a water-soluble inorganic salt supplied for dechlorination, photographic fixing and industrial processing. Confirm the required grade, then request a quotation with COA/TDS/SDS for bulk supply.

CAS: 7772-98-7
Synonyms: disodium thiosulfate, sodium hyposulfite, thiosulfuric acid disodium salt, sodium oxide sulfide, hyposulphite of soda
Einecs: 231-867-5
Molecular Formula: Na₂S₂O₃·5H₂O
Grade: Industrial / Technical / Photographic grade
Package: 25 kg woven bag or kraft bag with inner liner, 1,000 kg jumbo bag or as required

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Product Description

Sodium Thiosulfate, CAS 7772-98-7, also known as sodium hyposulfite or disodium thiosulfate, is a white crystalline inorganic salt; the EC/EINECS number is 231-867-5.

Synonyms: disodium thiosulfate; sodium hyposulfite; thiosulfuric acid disodium salt; sodium oxide sulfide; hyposulphite of soda.

CAS: 7772-98-7.

Molecular formula: Na₂S₂O₃·5H₂O.

Molecular weight: about 248.18 (pentahydrate).

EC number: 231-867-5.

It is a white crystalline granule or powder, odorless, freely soluble in water, with an assay typically ≥99.0% on a dry basis.

A 5–10% aqueous solution typically has a pH of 6.5–9.5, and the bulk density is about 1.6–1.8 g/cm³.

It loses crystal water and decomposes around 48–50 °C; it is stable under normal storage but incompatible with strong acids and strong oxidizing agents.

It is used as a dechlorinating agent to neutralize residual chlorine and chloramines in municipal, boiler, cooling and wastewater systems.

It is used as a photographic fixing agent, and in textile and paper processing including sulfur dyeing.

It is used as a reducing, neutralizing or complexing agent, and in iodometric titration and some metal recovery processes.

Confirm assay, appearance, water of crystallization, pH, chloride, sulfate, iron, heavy metals and insoluble matter; specify the technical, photographic or water-treatment grade.

Store in tightly closed bags in a cool, dry, well-ventilated area away from strong acids and oxidizers; use dust-control measures and suitable PPE when handling bulk material.

Confirm the current product-specific specification.

Confirm packaging with the requested quantity and destination requirements.

Document requirements should be confirmed from the current specification, SDS, COA or other product-specific files.

The page is an RFQ entry point and does not state stock, price, MOQ or fixed lead time.

For an RFQ, state the intended use, required specification, quantity, packaging, destination and document needs.

FAQ - Technical & Supply Chain

Q:
What form is Sodium Thiosulfate CAS 7772-98-7 supplied in?

A: Commercial sodium thiosulfate is commonly supplied as sodium thiosulfate pentahydrate, Na₂S₂O₃·5H₂O. The page uses CAS 7772-98-7, while some databases assign the pentahydrate CAS 10102-17-7, so confirm the physical form and water of crystallization before ordering.
Q:
How is sodium thiosulfate different from sodium sulfite?

A: Sodium thiosulfate contains the thiosulfate ion S₂O₃²⁻, while sodium sulfite contains SO₃²⁻. The additional sulfur changes its reducing, metal-complexing, and photographic-fixing behavior.
Q:
How is Sodium Thiosulfate used for dechlorination?

A: Sodium thiosulfate reacts with residual free chlorine and chloramines in water, wastewater, and aquaculture systems to form less harmful species. The required dose should be calculated from the measured chlorine residual and checked by testing to avoid overdosing.
Q:
What are the main industrial applications of Sodium Thiosulfate?

A: Sodium thiosulfate is used for dechlorination, as a photographic fixing agent, in textile and paper processing including sulfur dyeing, and as a reducing, neutralizing, or complexing agent. It is also used in iodometric titration and some metal recovery processes.
Q:
What specifications should be checked for Sodium Thiosulfate CAS 7772-98-7?

A: Confirm assay, appearance, water of crystallization, pH, chloride, sulfate, iron, heavy metals, and insoluble matter. Also specify the intended technical, photographic, or water-treatment grade and whether granules or powder are required.

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