• Chemistry 11.09.2008 1 Comment

    I don’t know what my motivation for this experiment was, but the outcome was surprisingly successful.

    Normally sodium is produced by electrolysis of an eutectic mixture of sodium chloride and calcium chloride, but this requires high temperatures of about 700°C.

    Sodium production 1. try

    Sodium production 1. try

    So I went for the so-called Castner process, which is based on electrolysis of molten sodium hydroxide. This requires only a temperature of about 330°C, which is easily achievable by an alcohol burner.

    To protect my table from spills of molten sodium hydroxide, I placed the bowl that contained the melt inside a metal can. To guarantee heat conduction and electrical contact i placed the bowl on top of some tin, which would then melt and provide good connection between the two cans.

    The cathode was a thick steel wire which was placed above the can.

    The first try was moderately successful. As you can see in the photos, a lot of blue crystals formed. I don’t know where they came from and they did not occur in the second try.

    Sodium production 2. try

    Sodium production 2. try

    A small droplet of molten sodium quickly formed at the cathode but it proved to be nearly impossible to get it out of the melt. I finally manged to get some out with a loop of wire. The sodium was immedatly put in molten wax to protect it from humidity.

    Next time i will try to build something resembling the draft from the wikipedia article to get better results.

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