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Q & A: Sodium and Chlorine

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Most recent answer: 05/16/2013
Q:
How do you combine soduim and cholorine
- Anonymous
A:
Very carefully and always watching out for safety! This particular pair, in their elemental form, are so dangerous I recommend that you do not even try to obtain either pure sodium or pure chlorine by themselves. For one thing, chlorine gas is extremely poisonous. It is used to kill bacteria in water in very low concentrations, and it is lethal to inhale the gas (it may even have been used in war to kill soldiers before it was banned by the Geneva convention).

Sodium is very reactive with air and water (and most air has some water in it!). Elemental sodium is usually stored in oil for this reason. When exposed to water, it combines so rapidly, it glows bright orange and may even explode. The explosion products include lye, NaOH, which is toxic and corrosive. Don't mess with this one either.

Just putting one of the most reactive metals in the same jar as one of the most reactive gases will almost certainly spontaneously ignite and explode, leaving -- you guessed it, ho-hum table salt, NaCl, which is perfectly safe, non-explosive, edible, and even necessary for life!

You can buy table salt at the grocery store, and by stirring it in water, you can separate the sodium ions from the choride ions, which stick to water molecules. But don't try making any salt from scratch! Salt comes ready-made from salt mines and by evaporating ocean water.

Tom

(published on 10/22/2007)

Follow-Up #1: sodium ions

Q:
As NaCl dissolves in water, it breaks into its separated sodium and "chloride" ions. The question I have is why isn't the sodium (now separated) dangerous in the water? Plus, if we can taste the salt in the water, then what are we tasting?...the sodium ion or the chloride ion? Are the ions considered harmless and only the "stable" elemental forms dangerous?
- Adult interested in learning (age 39)
Iowa
A:
The sodium is ionized, and much less reactive than a sodium atom with its full set of electrons. It's that last electron, not there in the ion, that is strongly reactive. In moderate amounts the ions aren't dangerous, although large amounts can raise blood pressure.
I believe the taste is mainly from the sodium ion, since KCl etc. taste somewhat different.
Mike W.

(published on 05/16/2013)

Follow-up on this answer.