NaK is the name of an alloy consisting of sodium and potassium, and an eutectic is formed, i.e., the mixtures of the two components have a lower melting point than the pure materials. It is in a wide range of concentrations at room temperature liquid and has been occasionally used for cooling nuclear reactors.

  • 3.1 coolant in nuclear reactors
  • 3.2 catalysis
  • 3.3 desiccant


Physical Properties

NaK mixture with a potassium content of between 40 % and 90% are liquid at room temperature. The eutectic is at a concentration of 22% and 78 % sodium potassium, has a melting point of -11 ° C and a boiling point of 785 ° C. The density is at 21 ° C 0.866 g / cm ³, the alloy is thus less dense than water. The surface tension is very high, so that the liquid has a tendency to form large drops.

Chemical Properties

NaK reacts as his constituents, sodium and potassium very easily with water and oxygen. When stored under air, a coating of yellow potassium superoxide is highly flammable forms. Since it is made of alkali metals, it is highly reducing.


Industrial NaK is produced by distillation. This liquid sodium and potassium chloride of a distillation column can be continuously supplied. In the reaction zone, the potassium chloride reacted with the sodium, so that sodium chloride and potassium arise. In the overlying rectifying section of the column, the boiling potassium is enriched and removed overhead as a mixture with sodium in any concentration.


Coolant in nuclear reactors

NAK is often used to cool working with fast neutrons experimental reactors. The low melting point is not necessary, an external heater for maintaining the liquid refrigerant when the reactor is shut down.


NaK can be used as a catalyst in various reactions, such as in the production of ibuprofen.


Due to the high reactivity with water, and the liquid state may be used as NaK dehydrating agent to remove residual moisture from solvents, such as tetrahydrofuran.