Gabriel Tojo wrote:
For those new to this thread, this was the first posting:
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 supporting
the wick theory, but Ralph Puchta from Bavaria passed me the following information:
łI never tried this experiment, but I'll report an explanation I found
in:
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 TojoIf you recall, I suggested the catalyst explanation very early in the
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
Eric Lucas schrieb am Mittwoch, 9. Oktober 1996 um 09:00:00 UTC+2:
Gabriel Tojo wrote:
If you recall, I suggested the catalyst explanation very early in
For those new to this thread, this was the first posting:
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
supporting the wick theory, but Ralph Puchta from Bavaria passed
me the following information:
łI never tried this experiment, but I'll report an explanation I
found in: 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
the 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
Hey guys, any new ideas regarding the problem? I am very interested
as I am unsure about showing students the combustion of sucrose with
ash as an example of a catalysed reaction.
On 02/05/2023 18:05, Jan-Hendrik Jördens wrote:
Eric Lucas schrieb am Mittwoch, 9. Oktober 1996 um 09:00:00 UTC+2:+1
Gabriel Tojo wrote:
If you recall, I suggested the catalyst explanation very early in
For those new to this thread, this was the first posting:
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
supporting the wick theory, but Ralph Puchta from Bavaria passed
me the following information:
łI never tried this experiment, but I'll report an explanation I
found in: 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
the 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
Hey guys, any new ideas regarding the problem? I am very interestedElephant's toothpaste aka decomposition of H2O2 by iodide is probably
as I am unsure about showing students the combustion of sucrose with
ash as an example of a catalysed reaction.
the most impressive catalysed reaction for getting students attention.
https://en.wikipedia.org/wiki/Elephant%27s_toothpaste
My instinct with this ash claim is that the ash is merely providing an
inert medium to be wetted and wick up melted sugar and with enough
surface area to facilitate ignition and burning away from the bulk hot molten sugar. Fumed silica or diatamaceous earth would be my choice of
test material to see which characteristic of the ash is important.
The B-Z reaction is also eye catching although takes some explaining
since Ce2+ self catalyses its own oxidation to Ce3+ which self catalyses
it own reduction to Ce2+. Aka a chemical clock that actually ticks from yellow to clear (or other colours with eg Ferroin in as an indicator).
The recipe is easy provided that your water is chlorine free.
Quite hypnotic in a petri dish on an OHP.
https://en.wikipedia.org/wiki/Belousov–Zhabotinsky_reaction
--
Martin Brown
Martin Brown schrieb am Dienstag, 2. Mai 2023 um 20:14:35 UTC+2:[snip]
On 02/05/2023 18:05, Jan-Hendrik Jördens wrote:
Eric Lucas schrieb am Mittwoch, 9. Oktober 1996 um 09:00:00
UTC+2:
+1more 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
Hey guys, any new ideas regarding the problem? I am very
interested as I am unsure about showing students the combustion
of sucrose with ash as an example of a catalysed reaction.
Elephant's toothpaste aka decomposition of H2O2 by iodide is
probably the most impressive catalysed reaction for getting
students attention.
https://en.wikipedia.org/wiki/Elephant%27s_toothpaste
My instinct with this ash claim is that the ash is merely
providing an inert medium to be wetted and wick up melted sugar and
with enough surface area to facilitate ignition and burning away
from the bulk hot molten sugar. Fumed silica or diatamaceous earth
would be my choice of test material to see which characteristic of
the ash is important.
The B-Z reaction is also eye catching although takes some
explaining since Ce2+ self catalyses its own oxidation to Ce3+
which self catalyses it own reduction to Ce2+. Aka a chemical
clock that actually ticks from yellow to clear (or other colours
with eg Ferroin in as an indicator). The recipe is easy provided
that your water is chlorine free.
Quite hypnotic in a petri dish on an OHP.
https://en.wikipedia.org/wiki/Belousov–Zhabotinsky_reaction
-- Martin Brown
I found an article from 1936 by Beyersdorfer (https://www.zobodat.at/pdf/Abh-naturforsch-Ges-Goerlitz_32_3_0021-0029.pdf).
He prepared sugar cubes with various substances (including SiO2) and
came to the conclusion that no catalytic effect could be proven, only
the wicking effect.
According to him, the important thing is that the substance used
prevents the sucrose from dripping off. He also claims to have
produced a candle consisting of sucrose.
I think it might be down to simple physics and also why many liquids
with lowish vapour pressure are difficult to ignite without a wick.
That candle made of sucrose sounds like an interesting test if slightly dangerous from a point of view of working with very hot concentrated
sucrose solution ~120C and some ordinary candle wick to make a sugar
candle by dipping.
Basically a lead washer on the end of a piece of wick dipped into a tall container of hot concentrated sugar solution a la jam making. Allowed to cool and keep going until you have a candle of sucrose. My betting is it will burn with a rather dirty flame but that it will work OK.
The problem otherwise is that the molten/dissolved in its own water of crystalisation sugar is a very good conductor of heat and so there is
always some more sugar to dissolve/melt at the interface. The wick
provides a location that is thermally isolated from the bulk liquid
where it can get hot enough for ignition and then away we go.
Do let us know if you manage this feat!
On Thursday, May 4, 2023 at 12:43:22 PM UTC-7, Martin Brown wrote:
I think it might be down to simple physics and also why many liquids
with lowish vapour pressure are difficult to ignite without a wick.
That candle made of sucrose sounds like an interesting test if slightly
dangerous from a point of view of working with very hot concentrated
sucrose solution ~120C and some ordinary candle wick to make a sugar
candle by dipping.
Basically a lead washer on the end of a piece of wick dipped into a tall
container of hot concentrated sugar solution a la jam making. Allowed to
cool and keep going until you have a candle of sucrose. My betting is it
will burn with a rather dirty flame but that it will work OK.
The problem otherwise is that the molten/dissolved in its own water of
crystalisation sugar is a very good conductor of heat and so there is
always some more sugar to dissolve/melt at the interface. The wick
provides a location that is thermally isolated from the bulk liquid
where it can get hot enough for ignition and then away we go.
Do let us know if you manage this feat!
Not exactly the same but isn't "sugar rock candy" often found on a string a suitable starting point?
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