Description
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Potassium is one of the alkali metals that occurs as a silvery white solid in its natural state. Potassium is highly reactive with water, and it tarnishes quickly when it is exposed to air. It is a light, soft, metal with an atomic weight of 39.0983, a melting point of 146.08 °F, and a boiling point of 1398 °F. The common uses of potassium include: in the production of low sodium salt, liquid detergents, and fertilizers, and as a superoxide in breathing apparatuses.
Isolation
Potassium is not found freely in nature. Instead, it is found in minerals and in potassium salt. Isolation processes used to isolate potassium include electrolysis and thermal methods.
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Potassium is frequently isolated on a large scale from extensive potash deposits that are located around the world. Potash contains impure forms of potassium carbonate in addition to other potassium salts. Electrolysis is the most common technique that is used to isolate pure potassium from potash; during this process, potassium hydroxide from potash is used.
Another process using thermal methods can be used to isolate potassium from potassium chloride. Potassium chloride can be extracted from potash; it is also found in the mineral sylvite. Electrolysis cannot be used due to the low reactivity of liquid potassium chloride. In this reaction, metallic sodium is reacted with liquid potassium chloride and heated to approximately 1562 °F. This process yields metallic potassium and sodium chloride.
Neither of these processes are usually carried out on a small laboratory scale as pure potassium can be purchased from large scale industrial isolations that are more energy efficient and cost effective.