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Sulfurous Acid

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.

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Sulfurous Acid Basic information

Product Name:
Sulfurous Acid
CAS:
7782-99-2
MF:
H2O3S
MW:
82.08
EINECS:
231-973-1
Mol File:
7782-99-2.mol
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Sulfurous Acid Chemical Properties

Density 
1.03 g/mL at 25 °C(lit.)
vapor density 
2.3 (vs air)
form 
Liquid
pka
1.92(at 25℃)
color 
Colorless
Water Solubility 
Miscible with water.
Sensitive 
Air Sensitive
Merck 
14,8976
Stability:
Stable. Incompatible with strong bases.
InChIKey
LSNNMFCWUKXFEE-UHFFFAOYSA-N
CAS DataBase Reference
7782-99-2(CAS DataBase Reference)
EPA Substance Registry System
Sulfurous acid (7782-99-2)
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Safety Information

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
10-23
TSCA 
Yes
HazardClass 
8
PackingGroup 
II
HS Code 
28111990

MSDS

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Sulfurous Acid Usage And Synthesis

Description

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

Uses

Dental bleach.

Uses

Sulfurous acid (H2SO3) can be produced by burning sulfur to form sulfur dioxide (SO2) gas and by then dissolving the gas in water to form sulfurous acid. This is the acid produced by burning coal that has a high sulfur content; the gaseous sulfur dioxide by-product of combustion then combines with atmospheric water to form “acid rain.”

Definition

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].

Hazard

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.

References

https://en.wikipedia.org/wiki/Sulfurous_acid
http://printwiki.org/Sulfurous_Acid
http://www.softschools.com/formulas/chemistry/sulfurous_acid_uses_properties_structure_formula/242/
https://pubchem.ncbi.nlm.nih.gov/compound/Sulfurous_acid#section=Top
http://www.chemistrylearner.com/sulfurous-acid.html

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Sulfurous AcidSupplierMore

Shanghai Aladdin Bio-Chem Technology Co.,LTD Gold
Tel:
021-20337333/400-620-6333
Email:
sale@aladdin-e.com
Products Intro:
Product Name:Sulfur dioxide solution
CAS:7782-99-2
Purity:AR, SO2>=6% Package:39RMB/500ML
Alfa Aesar
Tel:
400-610-6006; 021-67582000
Email:
saleschina@alfa-asia.com
Products Intro:
Product Name:Sulfurous acid, ACS, 6.0% SO{2} Min
CAS:7782-99-2
Package:500Ml Remarks:033275
Energy Chemical
Tel:
021-58432009
Email:
sales8178@energy-chemical.com
Products Intro:
Product Name:Sulfurous acid, ACS, 6.0% SO2 Min
CAS:7782-99-2
Package:500Ml,500Ml
Beijing Ouhe Technology Co., Ltd
Tel:
010-82967028-
Email:
2355560935@qq.com
Products Intro:
Product Name:SULFUROUS ACID
CAS:7782-99-2
Purity:98% Package:10g;50g;100g;250g;500g
Shanghai Hanhong Scientific Co.,Ltd.
Tel:
021-54308259- ;021-54306202-
Email:
info@hanhonggroup.com;info@hanhonggroup.com
Products Intro:
Product Name:sulfurous acid
CAS:7782-99-2
Purity:AR, SO2>=6% Remarks:RA03000026
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