Chk – 61 Toktabaeva Zarina

Plan of the lecture General Characteristics of Potassium Preparation of Potassium Occurrence Physical properties and Chemical properties Compounds of Potassium activity

Potassium was discovered in the autumn of 1807 by the English chemist Davy in the electrolysis of solid caustic potash. Humidifying the caustic potash, the scientist singled out the metal, which he called the potash, hinting at the production of potash from ash. Its usual name metal received two years later, in 1809, the initiator of the renaming of the substance was L.V. Gilbert, who proposed the name of potassium. KOH + Na = NaOH + К KCl + Na = NaCl + К

In the free state does not occur. Potassium is a part of all cells. Silvin KCl Sylvinite KCl · NaCl Carnallite KCl · MgCl2 · 6H2O Kainite KCl · MgSO4 ·6H2O Carbonate K2CO3 (potash) Mica Feldspar

Main isotopes of potassium

Potassium is a silvery substance with a characteristic sheen on a freshly formed surface. It is very light and easy to smelt. Relatively well dissolves in mercury, forming amalgams. Melting point K (63.5 °C, °F)K Boiling point 1032 K (759 °C, 1398 °F)

Interaction with simple substances: 2K + H 2 = 2KH K + O 2 = KO 2 3K + P = K 3 P Interaction with complex substances: 2K + H2O = 2KOH + H2 2K +2HCl= 2KCl + H2 Potassium deeply reduces dilute sulfuric and nitric acids: 8K + H 2 SO 4 = 4K 2 SO 4 + SO 2 + S+ H 2 O 21K +26HNO3 = 21KNO 3 + N 2 O + NO + N 2

Compounds with oxygen In the interaction of potassium with oxygen of air, not oxide forms but peroxide and superoxide: K + O 2 = KO 2 Potassium oxide can be obtained by heating the metal to a temperature not exceeding 180 ° C in a medium containing very little oxygen, or by heating a mixture of potassium superoxide and metallic potassium: KO 2 + 3K = 2K 2 O

Potassium hydroxide(caustic potash) Are obtained by electrolysis of KCl solutions, usually using mercury cathodes, which gives a product of high purity that does not contain chloride impurities: 2KCL + 2H 2 O = 2KOH + H 2 + Cl 2 Interaction with acids with formation of salt and water (neutralization reaction): 2KOH + H 2 SO 4 = K 2 SO 4 +2 H 2 O Interaction with acidic oxides with formation of salt and water: 2KOH+CO 2 = K 2 CO 3 + H 2 O

What mass of potassium halide can be used as potassium hydroxide of 148 kg with a mixture of 8% Equilibrium oxidation-decomposition reaction by electronic balance method: KO 2 + 3K = 2K 2 O