Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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magnalium : MgAl
phosphorus red : P
sulphur : S8
sulphuric acid : H2SO4
lead nitrate : Pb(NO3)2
copper sulfate penta hydrate : CuSO4 . 5H2O
cobalt nitrate : Co(NO3)2.6H2O
sodium chlorite : NaClO2
Class:
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elem=Cl
precipitation
coordination
Summary:
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Chlorite ion forms complexes with cobalt(II) and copper(II). It forms a
precipitate with lead(II). The precipitate with lead(II) forms a highly
energetic compound.
Description:
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Prepare a solution of sodium chlorite and set this aside for the experiments,
described below.
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Dissolve some cobalt nitrate and add some solution of sodium chlorite to this:
The solution changes from pink/rose to orange/brown in a time frame of appr.
10 seconds. After this change it becomes turbid and the color of the
precipitate formed in this reaction is very dark brown, almost black.
After a few minutes there is slow production of gas and the air above the
solution becomes pale yellow.
Add a little amount of dilute sulphuric acid: The dark precipitate quickly
dissolves, more gas is produced and the air above the liquid becomes intense
yellow (ClO2!).
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Dissolve some copper sulfate in water and add a solution of sodium chlorite:
The liquid quickly turns fairly dark olive green. It remains clear, also after
several minutes. No further reaction occurs.
Allow the solution to stand for several days: A grass-green solid has settled
at the bottom and a green/yellow solution remains present above the solid.
Decant the green/yellow solution and add some hydrochloric acid to the remaining
green solid: The solid dissolves. It does not dissolve at once, this takes a few
tens of seconds. The air above the liquid becomes yellow (ClO2).
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Dissolve some lead nitrate in water and add a solution of sodium chlorite.
Assure that there is excess solution of lead nitrate: A yellow precipitate is
formed. It is not a very bright yellow, it is more like finely powdered
sulphur, but its yellow color is slightly greyish.
Rinse the precipitate and allow to dry in warm air: The precipitate remains
yellow, it appears to be air-stable. It dries without problem and does not seem
to be hygroscopic. A fine yellow powder is formed.
Heat some of the powder on a small spatula above a flame of an alcohol burner:
The powder quickly 'burns', without visible flame. No residue is left behind,
a small amount of white smoke is produced.
Mix some of the powder with powdered sulphur. Take approximately equal volumes
of the powder of Pb(ClO2)2 and sulphur (just to the eye, no precise measurement
is needed). Ignite a small pile of the mix (appr. 4 mm x 4 mm x 3 mm of loose
powder): The mix explodes with a fairly loud bass noise (PHOMP). The light
output is not really strong. A bluish/grey flame is produced. The strength
of the sound and the strength of the explosion is impressive for a mix which
only contains sulphur as fuel.
Mix some red phosphorus with some of the lead chlorite. Do this VERY CAREFULLY
in a small aluminium cup of a tea light (waxine candle), by taking a very small
pile of lead chlorite (appr. 4 mm x 4 mm x 3 mm) with a similarly sized small
pile of dry and fine powder of red phosphorus and swirling the cup so that the
powders are mixed. Very carefully with a plastic stick of appr. half a meter
length take out half of this powder mix (WITHOUT SCRAPING!) and ignite it above
a flame of an alcohol burner: A very loud and impressive explosion occurs.
Very hot particles are sprayed around up to 50 cm from the center of explosion!
In a confined room the sound of the explosion may be so loud that the ears
start ringing afterwards. A small amount of white smoke is produced and light
output is stronger than with the sulphur mix, but it is not exceptional.
Repeat the last experiment with Al/Mg powder (magnalium 50/50), 400 mesh: This
mix burns very fast, but does not explode. It gives an incredibly bright white
flash when ignited. Ignition is easy, just as with the sulphur-mix.