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Inorganic acids

Sulfurous acid

Also known as Sulphurous acid, Schweflige saure, acide sulfureux

CAS 7782-99-2Formula H2O3SMolar mass 82.08 g/molEC 231-973-1
GHS signal word: Danger. Pictograms: Corrosive, Harmful or irritant 9 suppliers listed
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Sulfurous acid chemical structure, H2O3S, CAS 7782-99-2
2D chemical structure

Key facts

What buyers check first

All properties
Physical form
Liquid
Density
1.03 @25 °C
HS code
281119
Category
Inorganic acids
UN number
UN 1833
Illustrative photo, 200 litre blue HDPE drums of liquid in a warehouse
Typical packagingIllustrative packaging image, not the actual product

What is Sulfurous acid?

Plain description, key identifiers and synonyms

Sulfurous acid is a sulfur oxoacid. It is a conjugate acid of a hydrogensulfite. It is a tautomer of a sulfonic acid.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
sulfurous acid
CAS number
7782-99-2 CAS number cross-checkedOther or deprecated CAS: 14265-45-3
EC number
231-973-1
Molecular formula
H2O3S
UNII
J1P7893F4J
MDL number
MFCD00011335
InChIKey
LSNNMFCWUKXFEE-UHFFFAOYSA-N
InChI
InChI=1S/H2O3S/c1-4(2)3/h(H2,1,2,3)
SMILES (canonical and isomeric)
OS(=O)O

Synonyms

  • Sulphurous acid
  • Schweflige saure
  • acide sulfureux
  • acido sulfuroso
  • schweflige Saeure
  • trioxosulfuric acid
  • dihydroxidooxidosulfur
  • Sulfurous acid (h2so3)
  • Sulphurosum acidum
  • S(O)(OH)2
  • Sulfurous acid (II)
  • (SO(OH)2)
  • [SO(OH)2]
  • Trioxosulphate(IV)
  • Trioxosulphate(2-)
  • dihydrogen trioxosulfate
  • Sulfur dioxide 6 % solution
  • Sulfurous acid [UN1833] [Corrosive]
  • Sulfurous acid, SO2 (6.0%) in water

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Physical form
Liquidexp.
Density
1.03 @25 °Cexp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
82.08 g/molcalc.
Exact mass
81.9725 Dacalc.
LogP (octanol/water)
-0.32calc.
Topological polar surface area
57.53 Ųcalc.
Hydrogen bond donors
2calc.
Hydrogen bond acceptors
1calc.
Rotatable bonds
0calc.
Heavy atoms
4calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS05: Corrosive
Corrosive
GHS07: Harmful or irritant
Harmful or irritant

Hazard statements

  • H314Causes severe skin burns and eye damage.
  • H318Causes serious eye damage.
  • H332Harmful if inhaled.
Precautionary statements (16)
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P271Use only outdoors or in a well-ventilated area.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P330 + P331If swallowed: Rinse mouth. Do not induce vomiting.
  • P302 + P361 + P354If on skin: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316Get emergency medical help immediately.
  • P317Get medical help.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P363Wash contaminated clothing before reuse.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 1833
Transport hazard class
8
Packing group
II

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Sulfurous acid suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 9 suppliers
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Suppliers marked Unclaimed profile have not claimed their profile yet. They are not verified by CompoundList, their offers are price on request and details may have changed, so please confirm them with the supplier. Company representatives can claim a profile with a business email on the company's own website domain. Our team verifies each claim and sends the result by email.

Where suppliers are based

9 suppliers in 3 countries

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Sulfurous acid price

Indicative price range per kg from live supplier offers

No published prices right now

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Uses and applications

What the substance is used for, by industry and function

Industrial uses: Reducing agent.

Roles

  • Saccharomyces cerevisiae metabolite
  • animal metabolite
  • eukaryotic metabolite
  • fungal metabolite
  • human metabolite
  • mammalian metabolite
  • metabolite
  • mouse metabolite

Regulatory status

Inventories, regulations and trade controls that list this substance

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Sulfurous acid is traded under.

HS 2811.19Indicative HS code

Inorganic acids, other than hydrogen fluoride

World exports in 2024
$494M
+6.5% vs 2023, imports $458M
2019 to 2024
Top exporters
  1. China24.9%
  2. Israel16.0%
  3. Jordan * partner reported11.7%
Top importers
  1. China29.3%
  2. United States16.2%
  3. Germany7.0%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Sulfurous acid is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Sulfurous acid, based on the data on this page

What is Sulfurous acid?

Sulfurous acid is a sulfur oxoacid. It is a conjugate acid of a hydrogensulfite. It is a tautomer of a sulfonic acid.

What is the CAS number of Sulfurous acid?

The CAS registry number of Sulfurous acid is 7782-99-2. Other or deprecated CAS numbers: 14265-45-3.

What is the molecular formula and weight of Sulfurous acid?

The molecular formula of Sulfurous acid is H2O3S and its molar mass is 82.08 g/mol.

What is Sulfurous acid used for?

Industrial uses: Reducing agent.

Is Sulfurous acid hazardous?

Sulfurous acid carries the GHS signal word "Danger". Main hazards: causes severe skin burns and eye damage, causes serious eye damage, harmful if inhaled. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Sulfurous acid?

Sulfurous acid is usually classified under HS code 281119 (II. INORGANIC ACIDS AND INORGANIC OXYGEN COMPOUNDS OF NON-METALS, other). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Sulfurous acid?

CompoundList lists 9 suppliers of Sulfurous acid in China, United States and India. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Sulfurous acid in India?

1 supplier in India list Sulfurous acid on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Sulfurous acid?

Suppliers quote Sulfurous acid on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Sulfurous acid

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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