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Sigma-Aldrich

Sulfur dioxide solution

ACS reagent, ≥6%

Synonym(s):

Sulfurous acid, Sulfurous anhydride

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About This Item

Linear Formula:
H2SO3
CAS Number:
7782-99-2
Molecular Weight:
82.08
EC Number:
231-973-1
MDL number:
MFCD00011335
UNSPSC Code:
12352300
PubChem Substance ID:
329752746
NACRES:
NB.24

grade

ACS reagent

Quality Level

200

vapor density

2.3 (vs air)

Assay

≥6% SO2 basis (by Na2S2O3, titration)

form

liquid

concentration

≥6%

ign. residue

≤0.005%

density

1.03 g/mL at 25 °C (lit.)

anion traces

chloride (Cl-): ≤5 ppm

cation traces

Fe: ≤5 ppm
heavy metals (as Pb): ≤2 ppm

SMILES string

OS(O)=O

InChI

1S/H2O3S/c1-4(2)3/h(H2,1,2,3)

InChI key

LSNNMFCWUKXFEE-UHFFFAOYSA-N

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General description

Sulfurous acid (H2SO3), a weak diprotic acid, is formed when sulfur dioxide (SO2) dissolves in water. Sulfurous acid is a complex mixture of various hydrates of SO2 and the ions H3O+, S2O52- and HSO3-. The predominant species present in the solution are pH dependent.

Application

Sulfurous acid can be used as a reducing agent in chemical synthesis.

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Description
Pricing

Pictograms

CorrosionExclamation mark
GHS05,GHS07

Signal Word

Danger

Hazard Statements

H314,H332

Hazard Classifications

Acute Tox. 4 Inhalation - Eye Dam. 1 - Skin Corr. 1B

WGK

WGK 1

Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Certificates of Analysis (COA)

Search for Certificates of Analysis (COA) by entering the products Lot/Batch Number. Lot and Batch Numbers can be found on a product’s label following the words ‘Lot’ or ‘Batch’.

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The thermodynamic ionization constants of sulfurous acid at 25?1.
Tartar HV and Garretson HH.
Journal of the American Chemical Society, 63(3), 808-816 (1941)
M Kharina et al.
Applied biochemistry and biotechnology, 179(2), 307-320 (2016-01-29)
Sulfurous acid was used for pretreatment of sugar beet pulp (SBP) in order to achieve high efficiency of both extraction of carbohydrates and subsequent enzymatic hydrolysis of the remaining solids. The main advantage of sulfurous acid usage as pretreatment agent
Miquel Pascual et al.
Journal of the science of food and agriculture, 95(15), 3067-3076 (2015-07-16)
Rainfed viticulture, mainly in semi-arid environments, is limited by environmental variability, particularly precipitation and its seasonal distribution, and soil water availability, thus ultimately determining the final quality of grape and wine. Studies on the feasibility of practices such as canopy
Daniela Vullo et al.
Bioorganic & medicinal chemistry letters, 16(12), 3139-3143 (2006-04-20)
An inhibition study of the cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isozyme VII (hCA VII) with anions has been conducted. Cyanate, cyanide, and hydrogensulfite were weak hCA VII inhibitors (K(I)s in the range of 7.3-15.2 mM). Cl- and HCO3- showed
Heng Yu et al.
Bioresource technology, 199, 188-193 (2015-09-06)
This study established a new more neutral magnesium bisulfate pretreatment (MBSP) using magnesium bisulfate as sulfonating agent for improving the enzymatic hydrolysis efficiency of corn stover. Using the MBSP with 5.21% magnesium bisulfate, 170°C and pH 5.2 for 60 min
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