NaK

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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.

Properties

Chemical

NaK is pyrophoric and ignites immediately on contact with air.

Physical

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.

Availability

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

Preparation

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.

Projects

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

Handling

Safety

NaK is pyrophoric and highly dangerous to work with.

Storage

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.

Disposal

NaK is difficult to properly dispose of. Long chain alcohols can be used to neutralize it, as the reaction proceeds slow.

References

Relevant Sciencemadness threads