Molekula
Potassium sulfite
Supplying 4,500+ customers in over 80 countries
ISO 9001:2015 & ISO 14001:2015 certified · Supplying laboratories and industry since 1999 · Listed pack sizes are a starting point — we manufacture, source and repack to the quantity you need
Potassium sulfite (K₂SO₃) is an inorganic salt primarily used as a reducing agent, antioxidant, and preservative in food, pharmaceuticals, and water treatment. It prevents oxidation in dried fruits, wines, and processed foods, while also serving as a bleaching agent and corrosion inhibitor in industrial applications. This white crystalline powder has a CAS number of 10117-38-1, a molecular weight of 158.26 g/mol, and requires ambient storage. It carries a Warning signal word under GHS classification.
Molekula supplies Potassium sulfite at ≥95% purity in 1 kg packs, from £74.52 inc. VAT. It is in stock for same-day dispatch. Every batch ships with a certificate of analysis, and safety data sheets are available in 8 languages. Larger quantities, up to multi-tonne, are quoted on request.
Example image for illustration only. Other packaging and pack sizes are available.
Pricing & pack sizes
In stock — same-day dispatch
These pack sizes aren't a limit. Molekula manufactures, sources and repacks to order — if you need 500 kg and only see 1 kg listed, . We quote from grams to multi-tonne.
Need a different size? Add the nearest pack and change the size in your basket — we price it at the same rate per unit.
-
1 kg — £62.10 per pack ex VAT · £74.52 inc. VAT
Need a different quantity or pack?
Tell us how much you need and when — drums, IBCs, sacks or a one-off bulk lot. We'll manufacture or source it and come back with a price.
Prices exclude VAT/sales tax and shipping.
Specifications
| Property | Value |
|---|---|
| Appearance | White or off white powder |
| Assay | ≥95% |
| Water insoluble matter | ≤0.1% |
| Iron (Fe) | ≤0.1% |
| Thiosulphate (S2O3) | ≤0.05% |
Storage & handling
| Property | Value |
|---|---|
| Storage Temperature | Ambient |
| Acidity | Base |
Identification
| Property | Value |
|---|---|
| SKU | 90027069 |
| CAS Number | 10117-38-1 |
| IUPAC Name | dipotassium;sulfite |
| EC Number | 233-321-1 |
| Molecular Formula | K2SO3 |
| Molecular Weight | 158.26 |
| Exact Mass | 157.8842 |
| SMILES | [O-]S(=O)[O-].[K+].[K+] |
| InChIKey | BHZRJJOHZFYXTO-UHFFFAOYSA-L |
| InChI | InChI=1S/2K.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2 |
| PubChem CID | 24958 |
| REACH Code | Y110 |
| TSCA Listed | Yes |
| HTS Code | 2832200000 |
| Tariff Code | 2832200000 |
Safety & GHS
Hazard statements
- EUH031 Contact with acids liberates toxic gas
Precautionary statements
- P280 Wear protective gloves/protective clothing/eye protection/face protection
Documents
Safety Data Sheets (SDS)
Available in English, German, Spanish, French, Italian, Portuguese, Arabic, Dutch.
Certificate of Analysis (CoA) by batch
Enter a lot or batch number to retrieve the CoA for that specific batch. We can generate one from spec data if no PDF is on file.
Quality certificates
Molekula Group is certified to ISO 9001:2015 (quality) and ISO 14001:2015 (environmental management), audited by a UKAS-accredited body. Both certificates are valid to 17 May 2028.
Synonyms
- Dipotassium sulfite
- DIPOTASSIUM SULPHITE
- INS NO.225
- Kaliumsulfit
- Potassium sulfite (K2SO3)
- Potassium sulfite(IV)
- Potassium sulphite
- Sulfurous acid, dipotassium salt
- Sulfurous acid, potassium salt
- Sulfurous acid, potassium salt (1:2)
Frequently asked questions
What is potassium sulfite commonly used for?
Potassium sulfite (K₂SO₃) is primarily used as a reducing agent in photography, as an antioxidant in food and beverages, and in water treatment to remove chlorine and oxygen.
What is the molecular formula and molecular weight of potassium sulfite?
The molecular formula is K₂SO₃, and the molecular weight is 158.26 g/mol.
How should potassium sulfite be stored?
Store potassium sulfite in a cool, dry place at ambient temperature, away from moisture and incompatible substances like strong oxidizers.
What grades of potassium sulfite does Molekula supply?
Molekula supplies potassium sulfite with an assay of ≥95%, with limits of ≤0.1% water insoluble matter, ≤0.1% iron (Fe) and ≤0.05% thiosulphate (S2O3).
Can Molekula supply potassium sulfite in bulk quantities?
Yes, Molekula can supply potassium sulfite in bulk quantities, with packaging options including drums, bags, or custom solutions depending on order size.
What documentation comes with a potassium sulfite order?
Each order includes a Certificate of Analysis (CoA) and a Material Safety Data Sheet (MSDS).
Where can I buy Potassium sulfite?
Directly from Molekula, which lists Potassium sulfite in 1 kg packs from £74.52 inc. VAT, with a certificate of analysis for every batch. Larger quantities are quoted on request. Molekula's offices: United Kingdom, France, Spain, Germany, Italy, United States and China.
Ready to order or need a custom pack?
Tell us the product, grade, and quantity — Molekula usually responds within one working day with pricing and lead time.