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NaK (sometimes pronounced knack) or sodium-potassium alloy is, as its name suggests, an alloy of 77% potassium and 23% sodium which is liquid at room temperature.



NaK is pyrophoric and ignites immediately on contact with air. It reacts violently with water, alcohols and acids.


NaK is a silvery liquid, with a density of 0.866 g/cm3 at standard conditions. It melts at −12.6 °C and boils at 785 °C.


NaK is sold by various chemical suppliers, though it is not accessible to the amateur chemist, due to its fire hazard.


NaK can be made by mixing potassium metal with sodium, in a 77:23 ratio.

It can also be made through the electrolysis of an eutectic mixture of NaOH and KOH, or Na/K eutectic salt mix.


  • Demonstration of pyrophoricity
  • Dry solvents (dioxane e.g.)
  • Coolant (VERY DANGEROUS)



NaK is pyrophoric and highly dangerous to work with.


NaK can be stored under dry light mineral oil for several months. The oxidation of the alloy will also yield potassium superoxide which is very dangerous in the presence of moisture.

Ampouling is recommended to store this material.


NaK is difficult to properly dispose of, as it reacts violently with air, meaning that the neutralization cannot be done in open air, without a serious risk of fire, and instead must be done in an inert atmosphere or under inert solvent (like mineral oil or toluene). Long chain alcohols can be used to neutralize it, as the reaction proceeds slow.


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