potassium carbonate

Potassium carbonate
IUPAC name	Potassium carbonate
Other names	Potash, pearl ash
Identifiers
CAS number	584-08-7 Y
PubChem	516886
RTECS number	TS7750000
Properties
Molecular formula	K2CO3
Molar mass	138.205 g/mol
Appearance	white, hygroscopic solid
Density	2.29 g/cm3
Melting point	891 °C
Boiling point	decomposes
Solubility in water	112 g/100 mL (20 °C) 156 g/100 mL (100 °C)
Solubility	insoluble in alcohol, acetone
Hazards
MSDS	ICSC 1588
EU Index	Not listed
Main hazards	Irritant
NFPA 704	0 1 0
Flash point	non-flammable
LD50	1870 mg/kg
Related compounds
Other anions	Potassium bicarbonate
Other cations	Lithium carbonate Sodium carbonate Rubidium carbonate Caesium carbonate
Related compounds	Ammonium carbonate
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Potassium carbonate is a white salt, soluble in water (insoluble in alcohol), which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid. Potassium carbonate is used in the production of soap and glass.

History

Potassium carbonate was first identified in 1742 by Antonio Campanella and is the primary component of potash and the more refined pearlash or salts of tartar. Historically pearlash was created by baking potash in a kiln to remove impurities. The fine white powder remaining was the pearlash. The first patent issued by the U.S. Patent Office was awarded to Samuel Hopkins in 1790 for an improved method of making potash and pearlash.

In late 18th century North America, before the development of baking powder, pearl ash was used as a leavening agent in "quick breads".^[1]

Other terms for potassium carbonate:

• Carbonate of potash
• Dipotassium carbonate
• Dipotassium salt
• Pearl ash
• Potash
• Salt of tartar
• Salt of wormwood

Production

Today potassium carbonate is prepared commercially by the electrolysis of potassium chloride. The resulting potassium hydroxide is then carbonated using carbon dioxide to form potassium carbonate, which is often used to produce other potassium compounds.

2KOH + CO₂ → K₂CO₃ + H₂O

Applications

Pearl ash has been used for soap, glass, and china production.

Pearlash added to hard water will soften the water.^[2]

In the laboratory, it may be used as a mild drying agent where other drying agents such as calcium chloride and magnesium sulfate may be incompatible. However, it is not suitable for acidic compounds, but can be useful for drying an organic phase if one has a small amount of acidic impurity.

Mixed with water it causes an exothermic reaction.

It is mixed with distilled water to make a safer electrolyte for oxyhydrogen production than potassium hydroxide, the more commonly used electrolyte.

In cuisine, it is used as an ingredient in the production of grass jelly, a food consumed in Chinese and Southeast Asian cuisines.

Potassium carbonate is being used as the electrolyte in many cold fusion experiments.

Potassium carbonate is sometimes used as a buffering agent in the production of mead or wine.

Aqueous potassium carbonate is also used as a fire suppressant in extinguishing deep fat fryers and various other B class related fires.

Potassium carbonate is used in reactions to maintain anhydrous conditions without reacting with the reactants and product formed.^{[citation needed]} It may also be used to pre-dry some ketones, alcohols, and amines prior to distillation.^[3]

References

Bibliography

A Dictionary of Science, Oxford University Press Inc., New York 2003

External links

• International Chemical Safety Card 1588