I do not know how to understand the reasons of why a burned matchstick is attracted by a magnet (most probably) of Neodymium.
Here are some screenshots of a video in which this natural phenomenon is presented:
(In the video, see at 1 min 25 s):
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asked May 2, 2017 at 2:58
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1$\begingroup$ Don't think anything will be reduced on the match tip except the potassium chlorate. The heat and access to air will probably promote oxidation, not reduction of a species as noble as iron. If stackexchange allowed guesses, I would answer with something involving the antimon oxide residue and thermal magnetisation. +1 to the question, totally derailed me from work. $\endgroup$– StianMay 3, 2017 at 11:49
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$\begingroup$ Are you sure the video is not a fake? Camera trick? Modified matches containing iron? $\endgroup$– KartikMay 4, 2017 at 5:15
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$\begingroup$ The only thing that I can identify is that the magnet is of Neodymium $\endgroup$– Another.ChemistMay 4, 2017 at 5:18
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$\begingroup$ @StianYttervik Generally increased temperature should lead to less magnetism... $\endgroup$– ZheMay 4, 2017 at 14:57
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$\begingroup$ Its a mini thermite reaction iron III oxide used for pigment is converted to iron $\endgroup$– HectorDec 29, 2019 at 20:02
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1 Answer
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Some matchstick heads contain iron(III) oxide as a colorant.
The yellowish color of the burning match indicates that it has low oxygen, i.e. a reducing flame. It reduces the iron oxide to iron which is attracted by the magnet.
The reduction reactions that occur are probably quite complex. Below are two simplified possible reaction equations. $\ce{(CH2)_n}$ in equation (2) stands for paraffin from the splint's impregnation.
$$\ce{Fe2O3 + 3 CO -> 2 Fe + 3 CO2} \tag{1}$$
$$\ce{Fe2O3 + \frac{1}{n} (CH2)_n -> 2 Fe + CO2 + H2O} \tag{2}$$
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$\begingroup$ When you burn things you are oxidizing them not reducing them, right? Of course it's more complex than that. What we need to see in a full answer is how the flame has reducing and oxidizing regions, and where athend how the iron oxide gets reduced to get that iron which is attracted to the magnet. $\endgroup$ May 4, 2017 at 19:32
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$\begingroup$ Initially I was somewhat uncomfortable, the reason is that the links are hiding additional information. $\endgroup$– mykhalMay 4, 2017 at 19:38
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$\begingroup$ Can we get a summary of the key information in the links? For instance, "as seen here [link], a typical flame has both a fuel-rich reducing flame and an air-rich oxidizing flame, therefore the reducing flame will [insert its reaction with the iron (III) oxide]." That shows the logic up front without making the user chase down links. Common courtesy, IMHO. $\endgroup$ May 4, 2017 at 19:50
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1$\begingroup$ The reduction of iron oxide to iron involves many reactions, especially in the case with matchsticks where wood, paraffin, and different chemicals are involved. Added to simplified equations and hope they give hints what's going on. $\endgroup$ May 4, 2017 at 20:30