Types

• Potassium generally occurs as part of an ionic compound, a compound where one atom loses an electron to another so that the two each have a charge and are attracted to each other. Unfortunately, potassium is so easily oxidized that it's very difficult to separate from its compounds. The most practical way to purify potassium begins with a salt called potassium chloride.
  
  

Process

• Potassium chloride is a salt composed of chloride ions (chlorine atoms that have gained an electron from potassium) and potassium ions that have lost an electron to the chlorine. The salt is first heated to its melting point of 1,422 degrees Fahrenheit then exposed to vaporized sodium. The sodium reacts with the chlorine to form sodium chloride while the potassium is vaporized and removed from the reaction chamber.
  
  

Considerations

• The reaction chemists use to purify potassium works because potassium is more volatile than sodium, i.e. it evaporates more readily. By removing the potassium vapor from the reaction chamber as it forms, chemists decrease the concentration of the products of the reaction, which shifts the reaction to the right so that more pure potassium is produced. This technique is an application of Le Chatelier's principle, a principle chemists use to predict the results caused by a change in a system. The principle holds that a chemical system at equilibrium will shift in order to maintain equilibrium if the concentration of products or reactants is changed.