Potassium carbonate
- Potash
- Potassium carbonate
- KALI CARB
- E 501
White solid
Fixed
2.428 g · cm -3
891 ° C
Decomposition
Very well in water (1120 g · l -1)
Attention
1870 mg · kg -1 ( LD50, rat, oral)
-1151.0 KJ / mol
Template: Infobox chemical / molecular formula search available
Potassium carbonate ( technical terminology ) or potassium carbonate ( common language potash) K2CO3, is the potassium salt of carbonic acid. It is a white hygroscopic powder with a melting temperature of 891 ° C and a density of 2.428 g · cm -3. The name potash comes from the old method for the enrichment of potassium carbonate from wood ash by washing with water, followed by evaporation in pots ( pots ). The traditional name was also the inspiration for the English name of potash and potassium, with many potash mineral potassium salts including ( eg, potassium chloride), and it would be better translated as potash.
Occurrence
The world's largest deposits of potash ( potash ) are in Canada, Russia, Eritrea, Belarus and Germany; also in some inland waters such as the Dead Sea or the Lop Nor desert there is potassium carbonate. Previously potash was recovered predominantly of wood ash by leaching. The content of mineral components of wood ash is about 85%; about 14-19 % of which is potassium carbonate.
Production and representation
Potassium carbonate, sodium carbonate can not win as the ammonia- soda process, since the intermediate potassium bicarbonate ( KHCO3 ) is too soluble.
- Carbonation of potassium hydroxide:
- Reaction of lime (calcium hydroxide solution) with potassium sulphate and carbon monoxide at 30 bar ( Formiatverfahren ). The separated potassium is then calcined oxidatively:
- Leaching of plant ash, followed by evaporation in ash houses ( historically, technically no longer importance )
Properties
In water it is very light and highly soluble (1120 g / l). By hydrolyzing the solution reacts due to the formation of alkaline potassium hydroxide:
With acids to form carbon dioxide caused the corresponding potassium salts. At room temperature it crystallizes as the dihydrate from the aqueous solution.
Use
- An additive in the manufacture of glass
- Addition to soft soaps
- Production of Kaligläsern
- Production of paints
- Preparation of photographic developers
- Production of fertilizers ( kaliumliefernde component).
- Anhydrous potassium carbonate is sometimes used in laboratories as a drying agent.
- Raising agent for flat biscuits ( cookies and gingerbread, especially Christmas cookies ) and doughs with high sugar content.
- Addition to cocoa as an acidity regulator
- Neutralizing agent in the use of hydrochloric acid (E 507) as a flavor enhancer.
- Quick drying of raisins: By removing the natural wax coating of the grapes the moisture evaporates easily.
- Starting material for other potassium compounds.
- To remove crusts from pots: Add 1 tablespoon of the crust in the pan, allow to stand overnight and the next day boil with one cup of water; the residues decompose flaky bottom of the pot.
- Release agent for plaster casts (sculpture )
- Electrolyte component in Schmelzcarbonatbrennstoffzellen
- Approved tobacco additive for snuff tobacco, according to Regulation
- Additive for the ingestion of certain addictive substances
- Additive in some hand wash liquid soaps
- Environmentally friendly de-icing agents (instead of de-icing salt ) black ice on roads and sidewalks
Soda - potash digestion
The soda - potash digestion is fully annealed (acidic or amphoteric ) oxides, silicates, and silver halides used for poorly soluble ( alkaline earth ) sulfates; the digestion is carried out in a Na2CO3/K2CO3-Schmelze. ZrO2, Zr 3 (PO 4 ) 4, Al2O3, Cr2O3 and Fe2O3 are only partially resolved. For this melt digestion using soda and potash in the mixture, since to get over pure salts melting point depression is ( eutectic mixture ). In addition, the enormous excess carbonate pushing the reaction equilibrium to the product side.
An example of Sulfate: