He Potassium oxide , Also called dipotassium oxide, is an ionic salt of oxygen and potassium whose formula is K 2 O. Its structure is presented in figure 1 (EMBL-EBI, 2016).
The k 2 O is the simplest potassium oxide, it is a compound highly reactive and rarely found. Some commercial materials, such as fertilizers and cements, are tested by assuming the percentage of composition that would be equivalent to the mixture of chemical compounds K 2 OR.
Figure 1: structure of potassium oxide.
Potassium oxide is produced from potassium hydroxide (caustic potash) and metal potassium at 450 ° C producing molecular hydrogen (POTASSIUM OXIDE K2O, S.F.) according to the equation:
2K + 2KOH ⇌ 2K 2 O + H 2 (450 ° C).
It is also obtained by reducing the potassium peroxide according to the reaction:
2K 2 OR 2 → K 2 O + O 2 (530 ° C).
Another method of obtaining potassium oxide is by heating the potassium carbonate at high temperature as indicated by the following reaction:
K 2 CO 3 ⇌ K 2 O + CO 2 (T> 1200 ° C).
However, the main way of obtaining potassium oxide is by heating the potassium nitrate to obtain molecular nitrogen as indicated by the following reaction:
2KNO 3 + 10K → 6K 2 O + N 2
Physical and chemical properties of potassium oxide
Potassium oxide are tetrahedral crystals of yellowish color without a characteristic aroma (National Center for Biotechnology Information, 2017). Their appearance is shown in figure 2 (american elements, S.F.).
Figure 2: appearance of potassium oxide.
The compound has a molecular weight of 94.2 g / mol and a density of 2.13 g / ml at 24 ° C. It has a melting point of 740 ° C but begins to decompose at 300 ° C (Royal Society of Chemistry, 2015).
The compound is heat-resistant and soluble in ethanol and ether. K 2 O crystallizes in the antifluorite structure. For this reason, the positions of the anions and cations are reversed relative to their positions in CaF 2 , With potassium ions coordinated to 4 oxide ions and oxide ions coordinated to 8 potassium.
K 2 O is a basic oxide and reacts with water violently to produce caustic hydroxide. It is deliquescent and absorbs water from the atmosphere , Initiating this vigorous reaction.
Potassium oxide is reversibly oxidized to potassium peroxide at 350 ° C, reacts violently with acids, such as hydrochloric acid, to form potassium salts according to the reaction:
K 2 + 2HCl → 2KCl + H 2 OR.
The compound reacts with nitrogen dioxide to form nitrate and Potassium nitrite At temperatures between 150 and 200 ° C:
K 2 O + 2NO 2 = KNO 2 + KNO 3
Potassium oxide reacts at low temperatures with ammonia to form amides and potassium hydroxide according to the reaction:
K 2 O + NH 3 (L) → KNH 2 ↓ + KOH (-50 ° C).
Reactivity and hazards
Potassium oxide is an unstable substance. It oxidizes easily to other oxides of potassium, peroxide or acid oxide of potassium (KHO). The compound is not combustible but reacts vigorously and exothermically with the water to form potassium hydroxide (KOH).
The solution of potassium oxide in water is a strong base, reacts violently with acid and is corrosive. Reacts violently with water that produces potassium hydroxide. It attacks many metals in the presence of water (National Institute for Occupational Safety and Health, 2014).
The substance is corrosive to the eyes, skin and respiratory tract, as well as being ingested. Inhalation of aerosol may cause pulmonary edema. Symptoms of pulmonary edema often do not manifest until a few hours pass and are aggravated by physical exertion.
In case of contact with eyes, check for wearing contact lenses and remove them immediately. You should wash your eyes with running water for at least 15 minutes, with your eyelids open. Cold water can be used. Eye ointment should not be used.
If the chemical comes into contact with clothing, remove it as quickly as possible, protecting your own hands and body. Place the victim under a safety shower.
If the chemical builds up on the victim's exposed skin, such as the hands, gently and thoroughly wash contaminated skin with running water and non-abrasive soap. Cold water can be used. If irritation persists, seek medical attention. Wash the contaminated clothing before using it again.
If contact with the skin is severe, it should be washed with a disinfectant soap and cover the skin contaminated with an anti-bacterial cream.
In case of inhalation, the victim should be allowed to stand in a well-ventilated area. If the inhalation is severe, the victim should be evacuated to a safe area as soon as possible.
Loosen tight clothing such as a shirt collar, belts, or tie. If it is difficult for the victim to breathe, oxygen should be administered. If the victim is not breathing, a mouth-to-mouth resuscitation is performed.
Always taking into account that it can be dangerous for the person providing help give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive.
If swallowed, do not induce vomiting. Loosen tight clothing such as shirt collars, belts or ties. If the victim is not breathing, perform mouth-to-mouth resuscitation. In all cases seek immediate medical attention (IPCS, S.F.).
Applications
The chemical formula K 2 O (or simply"K") is used in various industrial contexts: N-P-K numbers for fertilizers, cement formulas and glass formulas.
Potassium oxide is often not directly used in these products, but the amount of potassium is reported in terms of K equivalents 2 Or for any type of potassium compounds used, such as potassium carbonate.
Potassium oxide is about 83% potassium by weight, while potassium chloride is only 52%. Potassium chloride provides less potassium than an equal amount of potassium oxide.
Therefore, if a fertilizer is 30 wt% potassium chloride, its standard potassium-based potassium oxide index would be only 18.8%. S And manufactures and / or imports between 10 and 100 tonnes per year of this substance in the European Economic Area.
This substance is used in laboratory chemicals, fertilizers, polymers and phytosanitary products. The K 2 Or it has an industrial use that results in the manufacture of another substance (use of intermediates).
Potassium oxide is used in the areas of formulation of mixtures and / or re-packaging and agriculture, forestry and fishing. This substance is used for the manufacture of chemicals, plastic products and mineral products (eg gypsum, cement).
The release into the environment of potassium oxide is likely to occur by industrial use: as an intermediate step in the manufacture of another substance (use of intermediates), formulation of mixtures, as processing aid and industrial processing of abrasion with low speed Textile release, cutting, machining or metal polishing).
Further release of this substance into the environment may be due to its use indoors, for example, machine wash liquids / detergents, car care products, paints and coatings or adhesives, fragrances and air fresheners.
Also for indoor use in closed systems with minimal release such as cooling fluids in refrigerators, oil-based electric heaters.
Potassium oxide is given an outdoor use in long life materials with low release rate eg building materials and construction of metal, wood and plastic.
In interiors, it is used in materials of long duration with low speed of release like for example furniture, toys, building materials, curtains, footwear, leather products, paper products and cardboard, electronic equipment.
This substance can be found in products made from stone, plaster, cement, glass or ceramic (eg plates, pots / pans, food storage containers, building materials and insulation) (European chemical agency, 2017).
Potassium oxide is a thermally stable, highly insoluble potassium source suitable for glass, optical and ceramic applications. Oxide compounds do not lead to electricity.
However, certain perovskite structured oxides are electronically conductive which find application in the cathode of solid oxide fuel cells and oxygen generation systems.
They are compounds containing at least one oxygen anion and one metal cation. They are extremely stable making them useful in producing ceramic structures such as clay bowls or for advanced electronics.
It is also used in light structural components in aerospace and electrochemical applications such as fuel cells in which they exhibit ionic conductivity.
The metal oxide compounds are basic anhydrides and can therefore react with acids and strong reducing agents in redox reactions.
References
- American elements. (S.F.). Potassium Oxide . Retrieved from americanelements.com.
- EMBL-EBI. (2016, September 19). Potassium oxide . Retrieved from ChEBI: ebi.ac.uk.
- European chemical agency. (2017, January 12). Dipotassium oxide . Retrieved from echa.europa.eu.
- (S.F.). POTASSIUM OXIDE . Retrieved from inchem.org.
- National Center for Biotechnology Information. . (2017, April 29). PubChem Compound Database; CID = 9989219 . Retrieved from pubchem.ncbi.nlm.nih.gov.
- National Institute for Occupational Safety and Health. (2014, July 1). POTASSIUM OXIDE . Retrieved from cdc.gov.
- POTASSIUM OXIDE K2O . (S.F.). Retrieved from allreactions.com.
- Royal Society of Chemistry. (2015). Potassium oxidopotassium . Recovered from chemspider.com.