| NaK | |
|---|---|
 |
|
| Identifiers | |
| CAS number | 11135-81-2 |
| Properties | |
| Molecular formula | Na + K |
| Molar mass | N/A |
| Appearance | Liquid metal |
| Density | 0.855 g/mL at 100Cº |
| Melting point |
-11Cº (12Fº) [1] |
| Boiling point |
785Cº (1445Fº) |
| Solubility in water | Reacts violently |
| Hazards | |
| Main hazards | Highly Reactive, Corrosive and Flammable |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
NaK (pronounced /næk/, rhyming with "sack") is a sodium (Na) - potassium (K) alloy usually liquid at room temperature.[2] Various commercial grades are available. NaK is highly reactive with air or water and must be handled with special precautions. Quantities as small as one gram can be a fire or explosion risk.[citation needed]
Contents |
Physical properties
NaK containing 40% to 90% potassium by weight is liquid at room temperature. The eutectic mix consists of 78% potassium and 22% sodium, is liquid from −12.6 to 785 °C, and has a density of 866 kg/m³ at 21°C and 855 kg/m³ at 100°C, making it less dense than water.[2] It is stored under mineral oil for safety reasons, and has a very high surface tension which makes large amounts of NaK pull into a bun-like shape.
Usage
As coolant
One notable use is as the coolant in experimental fast neutron nuclear reactors. Unlike commercial plants, these are frequently shut down and defuelled. Use of lead or pure sodium, the other materials used in practical reactors, would require continual heating to maintain the coolant as a liquid. Use of NaK overcomes this. NaK is used in many other heat transfer applications for similar reasons.[citation needed]
The Soviet RORSAT radar satellites were powered by a NaK-cooled reactor.[3] Apart from the wide liquid temperature range, NaK has a very low vapor pressure which is important in the vacuum of space.
The Danish computer cooling company Danamics use NaK in their CPU coolers.[4]
In catalysis
NaK is also used as a catalyst for many reactions, including precursors of ibuprofen.[citation needed]
As desiccant
Both sodium and potassium are used as desiccants in drying solvents prior to distillation. However, without heating, the solid metal is only able to react at the surface. Formation of oxide crusts also reduces the reactivity. As a liquid metal alloy at room temperature, the use of NaK as a desiccant helps to avoid these problems.[citation needed]
See also
References
- ^ "MSDS". http://www.youngshin.com/wwwboard/data/3/NaK-MSDS.pdf.
- ^ a b "Sodium-Potassium Alloy (NaK)". BASF. http://www.basf.com/inorganics/pdfs/tech_datasheet/NaK.pdf. Retrieved 2009-03-05.
- ^ Space.com article about RORSATs leaking NaK after jettisoning their reactor core. Retrieved 03/10/2009.
- ^ Danamics Liquid Metal Technology Retrieved 10/28/2009.
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