Potassium bisulfite

Not to be confused with potassium metabisulfite.

Potassium bisulfite

Names
IUPAC name Potassium hydrogen sulfite
Other names E228 Monopotassium sulfite Potassium bisulphite Sulfurous acid, monopotassium salt
Properties
Chemical formula	KHSO3
Molar mass	120.1561 g/mol
Appearance	White crystalline powder
Odor	Sulfurous
Melting point	190 °C (374 °F; 463 K) (decomposes)
Boiling point	Decomposes
Solubility in water	49 g/100 mL (20 °C) 115 g/100 mL (100 °C)
Solubility	Insoluble in alcohols, benzene, toluene
Hazards
Safety data sheet	CAMEO (solution)
Flash point	Non-flammable
Related compounds
Related compounds	Potassium sulfite Potassium bisulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium bisulfite or potassium hydrogen sulfite is a chemical compound with the chemical formula KHSO₃. The compound is commonly used in food industry, for sterilizing wine, as food additive E228. While it can be found as solid, it is more commonly encountered as solution.

Properties

Chemical

Potassium bisulfite oxidizes in air to potassium bisulfate.

Addition of a base raises the pH, converting the compound in potassium sulfite.

Physical

Potassium bisulfite is a white solid, with a sulfurous smell, soluble in water.

Availability

Potassium bisulfite is sold as both solid and solution, with the latter being more available. Make sure to check the product label/designation, as some products labeled as potassium bisulfite are actually potassium metabisulfite.

It is available as the food additive E228.

Preparation

Can be prepared by bubbling and excess of sulfur dioxide through a solution of potassium carbonate or potassium hydroxide.

Projects

• Reducing agent
• Make potassium bisulfate
• Make hydroxylamine

Handling

Safety

Potassium bisulfite releases toxic sulfur dioxide gas. Work in a well ventilated area or fumehood.

Storage

Should be stored in closed, air-tight bottles.

Disposal

Can be neutralized with bleach or hydrogen peroxide, then with a base to potassium sulfate.