Other
Projects:
Separating
Sodium from NaOH
First some
safety: The experiment described uses corrosive chemicals and mixtures
capable of burning without presence of atmosphere. It should be done
outdoors in cotton clothing as fire protection, with chemically
resistant gloves, and of course lab goggles. In case of fire, wait for
initial reaction to subside, then use a class D extinguisher - do not
attempt to put out fires with sand or water.
A recent experiment of mine involved the production of the highly
reactive element sodium from sodium hydroxide and another less reactive
metal, in this case magnesium. The reaction is as follows:
2Mg + 2NaOH = 2MgO + 2Na + H2
The magnesium (finely powdered) first ignites burning in atmospheric
oxygen contained in the reaction vessel. This initial reaction produces
enough energy to initiate the primary reaction. The Mg has enough desire
for the oxygen contained in the NaOH to actually rip it from the
hydroxide group, freeing hydrogen gas and sodium. The reaction is
violently exothermic. More than enough energy is released to ignite the
hydrogen gas which burns as the reaction progresses. The sodium is
produced in a liquid state due to the temperature of reaction, and some
of it vaporizes giving the flame a strong orange/yellow color.
To keep the sodium from burning immediately upon production, a loose
fitting lid is placed over the reaction vessel, allowing the burning
hydrogen to escape, but sealing the vessel off from atmosphere once
completed. The lid is then not removed until the reaction cools to air
temperature, at which point mineral oil should be added to the resulting
slag to prevent further oxidation of the product.
Presumably this experiment could be preformed with other metals acting
upon the hydroxide group, such as aluminum - in fact, I've heard
aluminum gives a better yield because of a lower reaction rate and
temperature which vaporizes much of the Na using Mg. I have not yet
tried it. It is also quite likely that this process could free most if
not all metals from their hydroxides because the reaction does not
involve the metal contained in the hydroxide, but the hydroxide group
alone. All hydroxides should therefore be susceptible to separation via
magnesium and possibly aluminum. I will conduct further experimentation
in warmer weather.
Here is a video of the experiment being conducted:
Ideally,
purification and removal of the sodium from the MgO slag would be as
simple as heating the mixture under mineral oil to the melting point of
sodium, at which point it would gather together. So far I have been
unable to do that successfully. It is possible the products needed to be
heated longer or they needed to be more finely ground beforehand to
free the sodium. Agitation is also a possible solution. Again, more
experiments will be preformed in warmer weather.