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Sulfurous Acid

Sulfurous Acid
Sulfurous Acid structure
Chemical Name:
Sulfurous Acid
Hso3;Hso3-;So3-2;sulfurous;SULFUROUS ACID;SULPHUR DIOXIDE;SULPHUROUS ACID;schwefligesaure;Schweflige Sure;SULFUROUS ACID 6%
Molecular Formula:
Formula Weight:
MOL File:

Sulfurous Acid Properties

1.03 g/mL at 25 °C(lit.)
vapor density 
2.3 (vs air)
1.92(at 25℃)
Water Solubility 
Miscible with water.
Air Sensitive
Stable. Incompatible with strong bases.
CAS DataBase Reference
7782-99-2(CAS DataBase Reference)
  • Risk and Safety Statements
  • Hazard and Precautionary Statements (GHS)
Hazard Codes  C,Xn
Risk Statements  20-34-36/38
Safety Statements  26-36/37/39-45
RIDADR  UN 1833 8/PG 2
WGK Germany  1
RTECS  WT2775000
HazardClass  8
PackingGroup  II
HS Code  28111990
Signal word: Danger
Hazard statements:
Code Hazard statements Hazard class Category Signal word Pictogram P-Codes
H314 Causes severe skin burns and eye damage Skin corrosion/irritation Category 1A, B, C Danger P260,P264, P280, P301+P330+ P331,P303+P361+P353, P363, P304+P340,P310, P321, P305+ P351+P338, P405,P501
H318 Causes serious eye damage Serious eye damage/eye irritation Category 1 Danger P280, P305+P351+P338, P310
H332 Harmful if inhaled Acute toxicity,inhalation Category 4 Warning P261, P271, P304+P340, P312
Precautionary statements:
P280 Wear protective gloves/protective clothing/eye protection/face protection.
P310 Immediately call a POISON CENTER or doctor/physician.
P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
P303+P361+P353 IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.
P405 Store locked up.

Sulfurous Acid price More Price(5)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 247626 Sulfur dioxide solution ACS reagent, ≥6% 7782-99-2 100g $62.9 2018-11-13 Buy
Sigma-Aldrich 247626 Sulfur dioxide solution ACS reagent, ≥6% 7782-99-2 2kg $203 2018-11-13 Buy
Alfa Aesar 033275 Sulfurous acid, ACS 6.0% SO2 min 7782-99-2 *4x500ml $239 2018-11-20 Buy
Alfa Aesar 033275 Sulfurous acid, ACS 6.0% SO2 min 7782-99-2 500ml $63 2018-11-20 Buy
Sigma-Aldrich 247626 Sulfur dioxide solution ACS reagent, ≥6% 7782-99-2 500g $111 2018-11-13 Buy

Sulfurous Acid Chemical Properties,Uses,Production


Sulfurous Acid is a weak and unstable inorganic acid, which is considered an aqueous solution of sulfur dioxide in water. It is formed theoretically by burning sulfur to produce sulfur dioxide, which is then reacted with water. However, there is no evidence that sulfurous acid exists in solution, while the molecules of which has been detected in the gas phase, since the reaction is reversible and the acid readily decomposes back into the reactants. Sulfurous acid is not usually available in its acid form, but more commonly prepared as its sodium or potassium salts.
Sulfurous acid and its salts are commonly applied as powerful reducing agents and disinfectant agents due to its strong reducibility. It is also considered as a mild bleaching agent especially for applications having chlorine sensitive materials. Besides, Sulfurous acid is a food additive listed on the EAFUS food Additive Database (Jan. 2001).

Chemical Properties

colourless liquid


Dental bleach.


A weak acid found only in solution, made by passing sulfur(IV) oxide into water. The solution is unstable and smells of sulfur(IV) oxide. It is a reducing agent, converting iron(III) ions to iron(II) ions, chlorine to chloride ions, and orange dichromate(VI) ions to green chromium(III) ions.

General Description

Sulfurous acid, H2S03, is an unstable, water-soluble, colorless liquid with a pungent burning sulfur odor. Corrosive to metals and tissue. It is derived from absorption of sulfur dioxide( S02) in water.Reagent grade sulfurous acid contains about 6% sulfur dioxide in solution. Sulfurous acid is a strong reducing agent.It is readily oxidized to sulfuric acid and is itself reduced to hydrogen sulfide by zinc and dilute sulfuric acid. Sulfurous acid is used in the synthesis of medicines and chemicals, in the manufacture of paper and wine, in brewing, in metallurgy, in ore flotation, as a bleach and analytical reagent, and for refining of petroleum products.

Air & Water Reactions

Soluble in water with release of heat.

Reactivity Profile

Colorless, corrosive, moderately toxic liquid. When heated to decomposition SULFUROUS ACID emits toxic fumes of oxides of sulfur [Lewis, 3rd ed., 1993, p. 1196].


Toxic by ingestion and inhalation, strong irritant to tissue.

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Industrial uses

Sulfurous acid (H2SO3) is usually marketed as liquid SO2. The bulk of SO2 is produced from off-smelter gases. Although handling of SO2 liquid requires special equipment, it is frequently used as a pH regulator and depressant, primarily during the treatment of complex sulfide ores. SO2 is largely used in North American operations as a pyrite depressant and for the depression of galena during copper/lead separation.

Safety Profile

A poison by ingestion and inhalation. A corrosive irritant to skin, eyes, and mucous membranes. Human systemic effects by ingestion: nausea or vomiting, hypermotility, diarrhea, and othergastrointestinal effects. When heated to decomposition it emits highly toxic fumes ofSOx.


Sulfurous Acid Preparation Products And Raw materials

Raw materials

Preparation Products

Sulfurous Acid Suppliers

Global( 114)Suppliers
Supplier Tel Fax Email Country ProdList Advantage
Mainchem Co., Ltd.
+86-0592-6210733 CHINA 32457 55
Hubei Jusheng Technology Co.,Ltd.
86-188-71490254 CHINA 20094 58
Shanghai Aladdin Bio-Chem Technology Co.,LTD 021-20337333/400-620-6333
021-50323701 China 24991 65
Alfa Aesar 400-610-6006; 021-67582000
021-67582001/03/05 China 30168 84
Energy Chemical 021-58432009 / 400-005-6266
021-58436166-800 China 44046 61
Beijing Ouhe Technology Co., Ltd +86-10-4006331231;+86-10-51280831;+86-10-82967028
+86-10-82967029 China 12500 60
Shanghai Hanhong Scientific Co.,Ltd. 021-54306202,021-54308259
+86-21-54291107 China 43266 64
Chengdu XiYa Chemical Technology Co., Ltd. 4008-626-111
028-84752058 China 9636 57
Tianjin heowns Biochemical Technology Co., Ltd. 400 638 7771 China 14464 57
Spectrum Chemical Manufacturing Corp. 021-67601398,18616765336,QQ:3003443155
021-57711696 China 9692 60

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