We frequently get amateur chemists posting here thinking they have found a way to make themselves some sodium, which they see as incredibly exciting because it reacts with water.
Most of these methods involve electrolysis. Let me explain, once and for all why this idea is wrong and foolish:
1) The reduction potential of sodium is very negative. This means that it likes to be Na+ and doesn't like to be Na at all. However, water has a much smaller reduction potential, and will easily be reduced to give hydrogen gas and hydroxide ions. The difference between the reduction potentials is so enormous that you will NEVER make sodium by reducing a sodium salt in water. You do however have a chance of making some chlorine at the other end if you decide to use sodium chloride. If you do this, you'll be making a very toxic gas which will burn your lungs in nasty ways. Be careful!
A side-point to aqueous electrolysis should be bloody obvious to people but it isn't. That is, that if you DID somehow miraculously manage to reduce sodium onto your cathode (perhaps you're Jesus), then it would immediately react with the water to make sodium hydroxide again, spitting and flames inclusive.
2) There is another method for making sodium and at least this one is actually possible. It is the electrolysis of molten sodium chloride. The trouble here is that while this is fairly easy to do on an industrial scale in specially built vessels, it's very difficult to do on a smaller scale, not to mention extremely dangerous. Molten sodium chloride is not pleasant, and it's very difficult to get to those kinds of temperatures. Sodium hydroxide was another suggestion I read on the forums, and while it certainly has a lower melting point, we're talking about a strong base here... do you REALLY want a molten puddle of fuming, spitting sodium hydroxide in front of you? REALLY? No. You don't.
3) Just because you can write and balance an equation it doesn't mean it will happen. The reasons behind what reactions will "go" and what reactions won't are quite detailed and beyond the scope of this thread. However, in general, things which are considered unstable (like sodium) are difficult to make (they require less stable things in the first place, or giant amounts of energy). So, NO, you can't make sodium by doing a simple displacement reaction or a precipitation reaction.
So all-in-all the net result of the above is NO! You CAN'T make sodium!
The above also applies to the other alkali metals
Edited by imatfaal, 9 June 2015 - 08:47 AM.
removal of chem tags that don't work now