Jan-Hendrik Jördens
2023-05-02 17:05:10 UTC
You approach a lighter flame to a sugar cube and it does not burn. But
if you apply previously some cigarette ash to the cube, it burns.
There must be some catalyst in the cigarette ash to sustain the
combustion of the sugar cube. Any idea?
It seems that there was a solid consensus within this group supportingif you apply previously some cigarette ash to the cube, it burns.
There must be some catalyst in the cigarette ash to sustain the
combustion of the sugar cube. Any idea?
the wick theory, but Ralph Puchta from Bavaria passed me the following
łI never tried this experiment, but I'll report an explanation I found
Hermann Römpp, Herrmann Raaf, Organische Chemie im Probierglas,
Franckh'sche Verlagsbuchhandlung Stuttgart, 1982, 15. Auflage. Page
108.
(A nice little book for interested persons.)
The author explanes, that he tested the problem himself and found that
a
few drops of FeCl3-solution will do the same job. So his idee was,
that iron
salts, you can find in cigarette ash, will behave as a sort of
catalyst. He
found that ZnO, K2CO3, Na2CO3, SiO2, and Pb(CH3COO)2 will work, too.
The author denies, that the ash will work as a wick. He thinks, that
if it would work like a wick, every similiar stuff like whitening
should allow to burnsugar cubes in
this easy way˛.
I will get hold of the article in the little book and tell the group
about it.
Gabriel Tojo
thread. My suggestion was alkaline oxides and carbonates deprotonating
the sugar alcohols, rendering them more susceptible to electron-transfer
oxidation. Apparently from what you say, acids work as well (e.g.
FeCl3). In this case, I would guess that acids catalyze the dehydration
of the sugar to an olefin or ketone, which can then undergo oxidation
more readily than an alcohol.
However, I thought the data in this case supported the fact that any
sufficiently high surface area solid that is wetted by sugar would
work. For example, I thought that someone said that talc worked.
Just because things that can act as catalysts will work doesn't mean
that is isn't still at keast partly a wicking phenomenon. The
definitive experiment is to try it with something that has little or no
chance of catalyzing the oxidation reaction--for example, very fine
fumed silica would be a good place to start (silated to rid the surface
of acidic--ie catalytic--functionality). Then if it burns under those
conditions, you have proven that the wicking phenomenon is at least part
of the explanation under some conditions.
Eric Lucas
I am very interested as I am unsure about showing students the combustion of sucrose with ash as an example of a catalysed reaction.
Jan Jördens