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    POTASSIUM
    19
    K
    39.0983 (1)


    Name: potassiumGroup number: 1
    Symbol: KGroup name: Alkali metal
    Atomic number: 19Period number: 4
    Atomic weight: 39.0983 (1)Block: s-block
    CAS Registry ID: 7440-09-7Voice:
    Standard state: solid at 298 KColour: silvery white
    Classification: MetallicAvailability:

    Nearing Zero cartoon for potassium
    Nearing Zero cartoon included by kind permission of Nick Kim.

    Isolation

    Here is a brief summary of the isolation of potassium.

    Potassium would not normally be made in the laboratory as it is so readily available commercially. All syntheses require an electrolytic step as it is so difficult to add an electron to the poorly electronegative potassium ion K+.

    Potassium is not made by the same method as sodium as might have been expected. This is because the potassium metal, once formed by electrolysis of liquid potassium chloride (KCl), is too soluble in the molten salt.

    cathode: K+(l) + e- K (l)

    anode: Cl-(l) 1/2Cl2 (g) + e-

    Instead, it is made by the reaction of metallic sodium with molten potassium chloride at 850°C.

    Na + KCl K + NaCl

    This is an equilibrium reaction and under these conditions the potassium is highly volatile and removed from the system in a form relatively free from sodium impurities, allowing the reaction to proceed.

    Fluorides
  • KF
  • Chlorides
  • KCl
  • Bromides
  • KBr
  • Iodides
  • KI
  • Hydrides
  • KH
  • Oxides
  • KO2
  • K2O
  • K2O2
  • Sulfides
  • K2S
  • Selenides
  • K2Se
  • Tellurides
  • K2Te
  • Nitrides
    none listed




    Our data and resources are taken from Web Elements