Potash - is the informal name of the substance that chemists call a potassium carbonate.This salt is known to people since ancient times, as it is contained in the ash.Earlier this word is called the dry residue after evaporation of the solution combustion plants.So, what is now known about potassium?
Formula
Another name for this substance - potash.And its chemical formula is written as - K2CO3.It represents the average potassium salt and carbonic acid.This means that the potash solution is not acidic or basic, it is neutral.For a long time it was confused with baking soda - NaHCO3.
history of discovery and study
Of course, we really do not know who got the first potash, as he was known in ancient Greece and Rome.Then it was recovered from the ash and used for washing.It is interesting that for a long time it was confused with another substance - potassium bicarbonate.The familiar baking soda, potash - together they were called just alkaline or alkaline salts.Distinguish between them began in XVIII-XIX centuries.For the first time this became known in 1759, when Andreas Marggraf found that the mineral ash is alkaline, while potassium - plant.And in 1807 Humphry Davy established the chemical composition of each of these substances.
first mention of the production of potash belongs to the XIV century.The largest companies are located in Germany and the Scandinavian countries.The potassium carbonate used in soap factories, cloth industry, dyeing plants.In the XV century in the competition including Russia.Before that allocate potash from the ash did not know how, but simply exported the products of combustion along with, for example, furs.Glass industry both in Russia and abroad also needed in this matter.Demand grew, and with it grew and demand.
By the way, the name "potassium" - this is just a hint method of its production in antiquity.The fact that it sounds like Latin potassa, which in turn is merging the words "ash" and "pot".
Chemical and physical properties
During the experiments with this substance scientists have received information about these or other qualities inherent in it.Today it is known that under normal conditions the pure potash - a solid in the form of colorless crystals or white powder.Its density - 2.43 g / cm3.The melting point of potassium carbonate - 891 degrees Celsius.It has a highly hygroscopic.
This material is not an explosion or fire hazard.After contact with moist skin or mucous causes irritation.Thus, it belongs to the third class of danger.
varieties and forms
are two types of potash: calcined and polutoravodny.In contrast to the second, first-form free of water - in the calcination process it evaporates and removes the organic substances in the resulting solution of potassium carbonate of this type becomes completely colorless.
In addition, potash and distinguish varieties emit only three.The quality of the final product depends on the content of impurities such as iron, aluminum, chloride, sodium and sulfates.Also taken into account when assigning grades mass fraction precipitated in solution and sediment loss on ignition.
Mining
Although the use of potash does not take place in such a massive scale, as is the case with baking soda, it is still widely used by people.But above all it needs to get.In small quantities it can be done even at home.
First of all you need to get their hands on the ashes of plant origin.Then you need to dissolve it in a certain amount of hot water, a good stir and wait for a while.Next you need to start to evaporate a solution of potash with a mixture of organic substances that cause loss of crystals.Of course, potassium carbonate, highlighted in this manner will not be of high quality, and the effort is too great in comparison with the number.So, it is saying industrial scale all occurs differently.
So potassium carbonate aqueous solution reacts with CO2, which leads to the formation of KHCO3.It, in turn, is heated, and the water is released and carbon dioxide in the residue - initial potash.
There are several ways to obtain this material, however the most simple and effective are those described previously.
Processing
As already mentioned, there are two types of potash - calcined and polutoravodny.How then is processed potassium carbonate to obtain a particular species?
outset differ even their formula.Polutoravodny looks: K2CO3 + 1,5H2O, ie it contains water initially.However, it is even more hygroscopic than normal.From this form can be prepared and anhydrous form - powder is sufficiently heated to 130-160 degrees Celsius.
calcined form obtained by treatment of potassium carbonate was prepared by evaporation of the solution in the ash wooden vats.This substance is not very clean, so it must either calcined or calcined.After carrying out one of these procedures, potassium carbonate powder turns white, and its solution was - completely colorless.In this case, the material does not contain water.
use
From ancient times to the present day, potassium carbonate is used in various forms in a large number of industries and with different objectives.For example, his wonderful ability to cleanse is still used in the manufacture of liquid soap and other household products.
In addition, potash - antifreeze additive to the mortar.As such, it enables mixtures to be more resistant to cold, which makes it possible to continue building even at fairly low temperatures.Its significant advantage over peers is that it does not cause corrosion of structures, as well as efflorescence, which could affect the strength of the structure.
still uses potassium carbonate in the manufacture of crystal and glass for high-quality optics.Substitutions in this case it is not.Nor is there any analogues of this substance, for example, in the manufacture of refractory glass.
Most potash - a component of paints and in the chemical industry it is used for the absorption of hydrogen sulfide from gas mixtures - he copes with it much better than soda.Is it a place in the pharmacy: potassium carbonate is involved in some reactions and appears somewhere as a byproduct.Another area of application - fire deal.It is this substance is treated wooden structures, thereby increasing their fire.
Surprisingly, but potash - it is also a food additive.Its code - E501 so that it belongs to a class of E. For a while it was used in the confectionery business, for example, in the manufacture of gingerbread.In light industry, the substance is also involved in the process of tanning.
Finally, the high prospects of application in the manufacture of chlorine-free potash potash.Ash as used in this long, but in recent decades it ousted feeding industrial production.Probably in the near future on a large scale will be applied a method known for a long time and is the least harmful in comparison with mineral fertilizers applied today.
Other features
Since potash - are extremely hygroscopic substance, its packaging, storage and transportation are held in special conditions.As a rule, for packing potassium carbonate used five-layer bags.The only way to avoid unwanted ingress of water into this substance.
Furthermore, surprisingly, despite the perfect reaction with H2O, potassium carbonate did not dissolve in acetone and ethanol.
