The violent reaction between sodium metal and chlorine gas to produce NaCl or table salt


The violent reaction between sodium metal and chlorine gas to produce NaCl or table salt


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About the Author: livescience

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  1. Explanation:

    This is one of those classical reaction you learn in school or university that’s still very cool to see in action. In this case a chunk of sodium metal is placed in an atmosphere of chlorine gas. Sodium atoms, as all alkali metals hang on to their outer electron rather loosely. More technically, they have a low [ionization energy](https://en.wikipedia.org/wiki/Ionization_energy). In contrast chlorine atoms not only hold on to their electrons very tightly, they really want an extra electron to get a full octet. In other words chlorine has a [high electron affinity.](https://en.wikipedia.org/wiki/Electron_affinity) The net result is that when you put (neutral) chlorine and sodium together, each chlorine atom will tend to snatch an electron from a sodium atom in order to form Na^(+)Cl^(-) or common table salt in the reaction:

    2Na(s) +Cl*_2_*(g) -> 2NaCl(s)

    Because the final product is more stable, a lot of energy is released in this process. In this case the release of this energy is nicely visualized by the bright flash that accompanies the reaction. However the fact that a reaction is energetically favorable doesn’t mean that it will happen right away. The reason is that there is a large barrier to starting this reaction. More technically you have to worry about the kinetics. If you just combine solid sodium and chlorine gas, you may wait until the cows come home until you see anything exciting. However you can speed things up by adding a catalyst. In this case that is exactly what the small droplet of water does. The water starts reacting with the outer layer of the chunk of sodium. Once this reaction starts releasing energy, the rest of the action quickly follows and the reaction between sodium and chlorine takes place in a flash.

    **Source for the GIF:** [This video](https://www.youtube.com/watch?v=tbPxwDiX1NU)

  2. So is it safe to eat the resulting salt? Or is there likely to be an excess of sodium metal or fused chlorine that would be harmful?

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