Originally published in Popular Science Magazine, reproduced with permission of the magazine and the author (that would be me).

Previous    Next    Story Index    Periodic Table Home
Popular Science Logo

Making Salt the Hard Way

Sodium + chlorine = your favorite popcorn condiment (and lots of smoke and fire!)


Scan
Sodium is a soft, silvery metal that explodes violently on contact with water and burns skin by reacting with even the slightest moisture. Chlorine is a choking yellow gas, used with mixed success in the trenches of World War I (it was known to have killed about equal numbers on both sides of the trench). When these chemicals meet, they react in a fierce ball of spitting fire and clouds of white smoke. The smoke is sodium chloride (NaCl), or table salt, which I used to season a basket of popcorn I hung over the reaction.

In the periodic table, as in politics, the unstable elements tend to hang out at the far left and the far right. Sodium is a loose-electron element from the first column (left side) of the table; its extra electron makes it unstable. On the other side of the table is chlorine, an equally volatile one-electron-short-of-a-full-deck element from the far-right 17th column. By transferring sodiuma^\200\231s excess electron to chorinea^\200\231s nearly full shell, the elements reach a stable configuration in NaCl. Salt doesna^\200\231t burn your skin or choke your lungs because, by combining with each other, both elements have scratched their itch.

As a way of salting popcorn, though, this kind of salt synthesis is pretty out there. The salt is very fresh, but the hazards of blowing pure chlorine into a bowl of liquid sodium are very real. Seconds after this picture was taken, the net melted, dropping popcorn into the bowl and sending a shower of flaming liquid sodium balls in all directions [see video below and the image gallery here]. No one was hurt because Ia^\200\231d made safety preparations for even the worst-case scenario, which this nearly wasa^\200'only an uncontrolled chlorine leak would have been worse, in which case I had a clear path to run like hell.
The Elements book Mad Science book Periodic Table Poster  Click here to buy a book, photographic periodic table poster, card deck, or 3D print based on the images you see here!