POTASSIUM METABISULFITE

POTASSIUM METABISULFITE
PRODUCT IDENTIFICATION
CAS NO.	16731-55-8
EINECS NO.	240-795-3
FORMULA	K₂S₂O₅
MOL WT.	222.30
H.S. CODE
TOXICITY
SYNONYMS	Dipotassium Disulfite; Disulfurous acid, Dipotassium salt;
Dipotassium disulphite; Dikaliumdisulfit; Disulfito de dipotasio; Disulfite de dipotassium; Potassium pyrosulfite; Pyrosulfurous acid, dipotassium salt;
DERIVATION
CLASSIFICATION
PHYSICAL AND CHEMICAL PROPERTIES
PHYSICAL STATE	white crystalline powder with odor of sulfur dioxide
MELTING POINT	190 C (Decomposes)
BOILING POINT
SPECIFIC GRAVITY	2.34
SOLUBILITY IN WATER	Freely soluble (450g/l)
pH	3.5 - 5
VAPOR DENSITY
AUTOIGNITION
NFPA RATINGS	Health: 1; Flammability: 0; Reactivity: 0
REFRACTIVE INDEX
FLASH POINT
STABILITY	Stable under ordinary conditions. Hygroscopic.
GENERAL DESCRIPTION & APPLICATIONS
Potassium metabisulfite is a white to slightly yellowish crystalline powder with sulfur dioxide odor; readily soluble in water. Potassium metabisulfite containing more than 56.0% SO₂ w/w releases sulfur dioxide gas when mixed with water. Their applications are almost same. Potassium metabisulfite's reductive and sulfonating properties provide applications of chemical formulations and for acidify fixation baths. Food grade potassium metabisulfite is used a preservative. It inhibits the growth of wild yeasts, bacterias, and fungi.
SALES SPECIFICATION
TECH GRADE
APPEARANCE	White to slightly yellowish crystalline powder
CONTENT	98.0% min
SO₂	55.0% min
K₂S₂O₄	0.5% max
pH	3.8 -4.6
Fe	5ppm max
FOOD GRADE
APPEARANCE	White to slightly yellowish crystalline powder
CONTENT	98.0% min
SO₂	56.0% min
K₂S₂O₄	0.05% max
HEAVY METALS	10ppm max
As	1ppm max
Fe	5ppm max
pH	3.8 -4.6
TRANSPORTATION
PACKING	25kgs or big bag
HAZARD CLASS
UN NO.
EUROPEAN LABELING IN ACCORDANCE WITH EC DIRECTIVES
`Hazard Symbols: XN, Risk Phrases: 22-31, Safety Phrases: 14`
OTHER INFORMATION
Sulfate (also spelled sulphate in Europe) is any chemical compound containing the SO₄^2- ion related to sulfuric acid (H₂SO₄). Sulfates are salts or esters of sulfuric acid, formed by replacing one or both of the hydrogens with a metal or a radical as in sodium sulfate, Na₂SO₄. Sulfates in which both hydrogens are replaced are called normal sulfates. Bisulfate is a compound that has the HSO₄^- radical. Bisulfate (called also hydrogen sulfate or acid sulfate) is a compound formed by replacing only one hydrogen in sulfuric acid. Sulfite (also sulphite) is a compound that contain the sulfite ion SO₃^2-. Sulfites are salts or esters of sulfurous acid (H₂SO₃), formed by replacing one or both of the hydrogens with a metal or a radical as in sodium sulfite, Na₂SO₃. Sulfites in which both hydrogens are replaced are called normal sulfites. Bisulfite is a compound that has the HSO₃^- radical. Bisulfate (called also hydrogen sulfite or acid sulfite) is a compound formed by replacing only one hydrogen in sulfurous acid. The term of 'meta' or 'pyro' is the chemical prefix for oxo acid formed through the loss of one water molecule (dehydration) from two molecules of ortho acid by heating. Pyrosulfuric acid is an example ( 2H₂SO₄ - H₂O = H₂S₂O₇). Ortho acid is the compound fully hydrated acid or its salts. Orthophosphoric acid is an example (2·H₃PO₄ = P₂O₅^.3H₂O), in contrast to the less hydrated form, pyrophosphoric acid (2·HPO₃ = P₂O₅^.H₂O). Na₂O₅S₂ is called sodium metabisulfite (2·HNaO₃S - H₂O). Sulfide is a compound having one or more sulfur atoms in which the sulfur is connected directly to a carbon, metal, or other nonoxygen atom; for example sodium sulfide, Na₂S. Sulfide ion is S^2- with oxidation number -2. Bisulfide ion is an anion formed by two sulfur atoms having an overall -2 charge, (S₂)^2-. Sulfamate is a salt of sulfamic acid (HSO₃NH₂). Calcium sulfamate Ca(SO₃NH₂)₂ is an example.