MSDS Sodium Thiosulfate (Na2S2O3) – Safety Data Sheet & GHS Hazards

Summary MSDS for Sodium Thiosulfate (Na2S2O3), CAS 7772-98-7: substance identity, GHS hazard classification, hazard and precautionary statements, and links to the manufacturer's official SDS.

Identity summary

Name	Sodium Thiosulfate
Other names (IUPAC)	disodium;dioxido-oxo-sulfanylidene-lambda6-sulfane
Molecular formula	Na2S2O3
CAS number	7772-98-7
Molar mass	158.11 g/mol
PubChem CID	24477

Molar mass of Na2S2O3 and how to calculate it

The molar mass of Na2S2O3 is 158.11 g/mol, the sum of the relative atomic masses of all atoms in the formula: 2 × 22.990 + 2 × 32.065 + 3 × 15.999 = 158.11 g/mol.

Element	Atoms	Atomic mass	Contribution	Mass %
Na	2	22.990	45.98	29.08%
S	2	32.065	64.13	40.56%
O	3	15.999	48.00	30.36%

So 1 mol of Na2S2O3 weighs 158.11 g, and 1 L of a 0.1 M solution needs 15.811 g of pure Na2S2O3. For liquid or concentrated reagents, work from assay and density with the dilution formula. Calculate other compounds with the molar mass calculator.

Hazard identification (GHS)

This substance does not meet the GHS hazard criteria according to TCI official data. Still follow good laboratory practice: wear a lab coat and safety glasses and keep it in a closed, labelled container.

The GHS classification above matches TCI (Tokyo Chemical Industry) official data for product O0522 Sodium Thiosulfate Pentahydrate. Substance identity from PubChem CID 24477.

Download the official SDS & CoA

The applicable Safety Data Sheet is the manufacturer's SDS for the product and lot you purchase. For products available from AMI Scientific:

TCI O0522 – Sodium Thiosulfate Pentahydrate	Official SDS & CoA (TCI)
TCI O0522 – Sodium Thiosulfate Pentahydrate	View product
Sodium Thiosulphate Pentahydrate, CAS 10102-17-7, 1 kg – Smartlab A-2056	View product

SDS and lot-specific CoA are sent with the quotation/order or on request.

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What is an MSDS/SDS?

An MSDS (Material Safety Data Sheet), now called an SDS (Safety Data Sheet), is a 16-section document describing the hazards, handling, storage, first aid, and disposal of a chemical. Read the full MSDS guide and other MSDS pages.

This summary was compiled by AMI Scientific from TCI official GHS data for information purposes. Classification may differ by concentration, form, and supplier. Always refer to the manufacturer's official SDS for the product and lot you use. Updated: 06-11-2026.