Yeah it kind of defeats the point when your definition of 'doesn't burn' covers every single substance.
Monopropellants, that aren't mixtures, exist and "burn" too, high concentration H2O2 for instance.
Pretty much any combustion requires a molecule with oxygen to accept the electrons: exceptions exist with halogens like chlorine… but these are still called “oxidizers”
So saying hydrogen doesn’t burn without an oxidizer still makes little sense. Hydrogen will combust with either oxygen or chlorine for example, both oxidizers. Without those then nothing happens because nothing can combust without an oxidizer… You may just not realize the oxidizer is mixed with the fuel.
Sulfur is commonly used as an oxidizer for metal fuels. In the case of gunpowder, that would be the potassium in potassium nitrate.
https://www.wikipedia.org/wiki/Gunpowder#Components
Potassium nitrate is the most important ingredient in terms of both bulk and function because the combustion process releases oxygen from the potassium nitrate, promoting the rapid burning of the other ingredients
Sulfur's main role in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be:
6 KNO3 + C7H4O → 3 K2CO3 + 4 CO2 + 2 H2O + 3 N2Sulfur is commonly used to bootstrap exothermic reactions, largely based on its strong affinity for oxidizing metals with relatively low activation energy. In gunpowder, you need the potassium nitrate to release the “nitrate” part so that it can oxidize the carbon but for that to happen you need to offer potassium something more thermodynamically attractive to bind to. Charcoal (carbon) cannot serve that purpose. Sulfur provides that thermodynamically attractive outlet for potassium such that it will happily release the nitrate. Sulfur, in this case, would be termed a “sensitizer” but the mechanism of action is as a metal oxidizer. Sulfur/metal complexes are often used to bootstrap hard-to-ignite things such as thermites.
There are many metal oxidizer salts that become so sensitized in the presence of sulfur that they become dangerously unstable. In the case of potassium nitrate, it becomes more sensitized but still stable enough to be useful. For most real industrial applications, metal oxidizer salts have long been replaced with ammonium oxidizer salts which don’t have any metals to worry about.
The “sulfur-free” formulation uses an organic fuel (gunpowder does not), which provides alternative potassium sinks thereby obviating the need for sulfur.
I’m not. I’ll give the benefit of the doubt we have a miscommunication though.
> Technically speaking, sulfur is an oxidizer in gunpowder, not fuel.
This initial statement makes it sound like you were claiming that the potassium nitrate is not the primary oxidizer in the combustion. It is the potassium nitrate’s role which is the oxidizer and not the fuel.
And yes, sulfur attracts the potassium, and aids in the reaction, but it’s role is also as fuel, which you incorrectly stated it was not.
Again, from wikipedia:
sulfur (S), which, while also serving as a fuel, lowers the temperature required to ignite the mixture, thereby increasing the rate of combustion. [1]
[1]https://en.m.wikipedia.org/wiki/Gunpowder#Components
And Fuel:
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work.
Sulfur itself can be burned. Potassium nitrate cannot. In fact if you add sulfur to potassium nitrate the sulfur can act as the reducing agent and you’ll get sulfur dioxide.
4KNO3+5S⟶2K2O+5SO2+2N2
Gunpowder (specifically black powder) works in a vacuum because of the potassium nitrate, not because of the sulfur. You can have gunpowder without sulfur, but it’s not going to work without the potassium nitrate.
Gave a fairly full reply to this over here
Anyway, as long as you understand that’s not what is meant by the term burning I don’t really think there is anything worth arguing about here. And hey in 100 years your definition might win.
> that’s not what is meant by the term burning
Monopropellants may not agree with your use of the term burning, but I deny that they do not agree with the majority of english speakers use of the word burning, or the definition of the word burning that you will find in common dictionaries [1].
[1] For example merriam-webster defines "burning" as "being on fire", "fire" as "the phenomenon of combustion manifested in light, flame, and heat" and "combustion" as "a usually rapid chemical process (such as oxidation) that produces heat and usually light".
For anyone reading this I will say Wikipedia and at no point is combustion or burning used do describe them. “Monopropellants[1] are propellants consisting of chemicals that release energy through exothermic chemical decomposition” https://en.wikipedia.org/wiki/Monopropellant
Although I am enjoying the side discussion about monopropellants.
Mono-propellant, and solid (not hybrid) rocket fuel fits the description though
Decomposition doesn’t count as “burning” which means combustion. Fusion and fission release energy as well, but I don’t think anyone calls fusion “burning” hydrogen.
I'll make an exception and reply about the language in this case because I there's a broader point I want to make:
English isn't a language defined based of "X happens if chemical reactions Y happens behind the scenes", because we didn't even know about chemical reaction Y when English was invented. Moreover if you tried to define it as oxidation you'd fail, rust isn't burning, meanwhile (non-oxidizing) chemical burns, sunburns, etc all exist because they were just analogous enough to the concept of fire. If people knew about some chemical that decomposes into plasma in the 1600s, they definitely called it burning even if there was no oxidation.
Meanwhile people definitely refer to fusion as "burning", e.g. see this stackexchange question with lots of links to wikipedia and the like which refer to different kinds of fusion as burning [1] or ctrl-f burning in this wikipedia article [2] (which is linked from [1]).
[1] https://astronomy.stackexchange.com/questions/43907/hydrogen...
Someone who says the following isn’t just using language inaccurately, it actually shows a fundamental misunderstanding of combustion:
> pure hydrogen doesn’t burn. It needs an oxidizer—like the oxygen in air.
That statement, no matter how you take it, leaves an assumption that other gases might burn like hydrogen without oxygen, which is again a fundamental misunderstanding of chemistry.
In addition calling something “self oxidizing” doesn’t make sense. There are always mixtures of fuel and oxidizers… whether those are gas and fuel, solid and fuel, mixed in gunpowder form, mixed as gasoline and air in a carburetor, etc. So if I supply you a balloon with the proper stoichiometric ratio of gasoline and air, is that “self-oxidizing”? If so then everything is self oxidizing.
And while I would agree that people do refer to fusion as “burning” I actually think this is a again a prime example of people not understanding the underlying physics. Most people don’t understand how fusion works, so calling it “burning” is a lazy way to conceptualize what the sun is doing. Scientists will sometimes use “burning hydrogen” when talking about nucleosynthesis, but they assume the audience of other scientists understand the difference between combustion and fusion.
When articles like the original post are talking to the layperson in this manner however, it does nothing but lead to more scientific illiteracy. A perfect example is one of the above comments:
> There are rumours that because of this fact, that the Hindenburg disaster was not from natural causes.
If we don’t communicate science effectively then we end up with conspiracies and pseudoscience. Words are tools. They should be used wisely.
It is when "burning" just means "fast reaction that creates something like a flame"... the vast majority of your post relies on a definition where it does not.
> That statement, no matter how you take it, leaves an assumption that other gases might burn like hydrogen without oxygen,
There are at least two ways to read this statement where that is incorrect.
One is to use the merriam-webster definition (see another one of my comments in this thread where I tracked that down) of burning (which includes things like H2O2 decomposing) instead of your definition.
The other is to include non-pure gasses, like a mixture of H2 and O2. Or if you somehow managed to vaporize gunpowder without it igniting.
A potential third is if you managed to make a chemical with an oxidizing agent on one end, and a reducing agent on the other... which now that I think about it sounds technically possible (if very difficult).
> And while I would agree that people do refer to fusion as “burning” I actually think this is a again a prime example of people not understanding the underlying physics.
Fusion researches call it burning, so with respect I think you're just wrong, they just understand the word burning to mean something other than what you do.
Consider also that things "burn up" upon re-entry from space (I'm sure anything oxidizable oxidizes, but mostly that means they vaporize), that you get rope burn, that ablative heatshields burn up, ... (I'm sure I could come up with more given some time)
> If we don’t communicate science effectively then we end up with conspiracies and pseudoscience. Words are tools. They should be used wisely.
I agree, but I think you are doing the exact opposite of what you want to to achieve this goal.
Redefining words so that they have a cleaner scientific definition makes it easier to talk about things precisely within the "in-crowd" who have accepted your redefinition. It confuses, annoys, and generally makes the "out" crowd feel stupid. That confusion makes it easier to get them to accept conspiracies and pseudoscience, making them feel stupid makes them less likely to listen to you (as a whole group) when you try and show them why they are wrong. This is counter-productive.
This is a common trend in "academic language", and I really think it does untold damage in peoples trust in these illiterate experts who keep insisting on facts that are simply wrong in the language called English that everyone else speaks (Peanuts are in fact nuts, Tomatoes are in fact vegetables and not fruits, and so on and so forth).
I’m not trying to put down anyone in the “out crowd”. It’s simply that if we want to talk about scientific subjects, then we need to use precise language. Math has its own language. Science uses math in many areas, which removes ambiguity. Unfortunately English and other languages are the best we have when communicating other topics, which is why it’s best to be very precise.
I understand all the points you make and I agree with some of them in many respects (I was an undergraduate English major)
It’s simply that the use of imprecise English terms when talking about science specifically with the general public often does more harm than good. For instance:
> A potential third is if you managed to make a chemical with an oxidizing agent on one end, and a reducing agent on the other... which now that I think about it sounds technically possible (if very difficult).
This lacks an understanding of redox reaction chemistry, since it’s not possible. Salt is NaCl, the Cl being an oxidizer and the Na being a reducer. You can’t cause salt to self combust. It’s just not possible. In this case we need to turn to more precise language, and the use of chemical formulas to explain why. It’s the perfect example of how in plain English something like you described sounds possible, but comes from a confusion introduced by the language. As a further example let’s say you mean that the oxidizer is on a remote far end of the molecule. Then what your are again talking about is that molecule acting as an oxidizer. If you want to imagine some large molecule with a strong reducing component on one end and a strong oxidizing component in the other, that also can’t “self oxidize” because it would be in constant reaction with itself. (To be even more specific requires even more specific language that is too much for one reply.. for example you can have molecules that get reduced and oxidized in something called a disproportionation reaction, but you’ve basically got multiple reactions happening with multiple products)
> I really think it does untold damage in peoples trust in these illiterate experts who keep insisting on facts that are simply wrong in the language called English that everyone else speaks.
Peanuts are legumes in a biological sense. It’s an important distinction because it matters about the types of proteins that peanuts contain (and tree nuts do not). This is due to bacteria in the roots that are able to fix nitrogen. So again, this is not about academic language… it’s about being clear and precise when it matters to talk about how the world actually is rather than how we perceive it.
Edit:
> It confuses, annoys, and generally makes the "out" crowd feel stupid. That confusion makes it easier to get them to accept conspiracies and pseudoscience, making them feel stupid makes them less likely to listen to you (as a whole group) when you try and show them why they are wrong. This is counter-productive.
I think there are many reasons for this, but I don’t think using clear and precise language is to blame. I think for one our society puts a stigma on saying “I don’t know”. No one should feel stupid for saying that, since it’s the start of all knowledge, and as a society we need to teach that.
I also think that the education system still does a poor job on science education in general. So very smart people end up unable to decide between “purveyors of knowledge”. If we judge arguments solely on their oratorical value, it’s easy to be mislead.
A great change to our education system would be better teaching of logic and biases, something like the following:
I doubt that, at least to the extent it's been used in this discussion.
> This lacks an understanding of redox reaction chemistry, since it’s not possible. Salt is NaCl, the Cl being an oxidizer and the Na being a reducer. You can’t cause salt to self combust. It’s just not possible.
I agree it doesn't occur with salt, that doesn't mean it can't happen. 2 Sn2+ → Sn4+ + Sn looks to be an example.
I was actually imagining something more along the lines of H3C-CH2-CH2-CF3 managing to have the F3 end oxidize the H3 end (I strongly suspect that specific example doesn't work) - I'll ask the chemists in the house if they know of any such reactions tomorrow since Google isn't being much use... but it's certainly seems like it should be able to.
> Peanuts are legumes in a biological sense. It’s an important distinction because it matters about the types of proteins that peanuts contain (and tree nuts do not). This is due to bacteria in the roots that are able to fix nitrogen.
Agreed
> So again, this is not about academic language
Choosing to try and label "peanuts" as not "nuts" is. Introducing the phrase "tree nuts" is a much better way to be clear and precise, because you aren't trying to declare things that use to be nuts, not nuts anymore, and hoping that everyone will go along with it.
> but I don’t think using clear and precise language is to blame
It's not the use of clear and precise language which is to blame, it's the attempt to redefine existing imprecise language in an incompatible way to make it precise that is to blame.
I'm all for adding a discussion of logic to math, and fallacies/biases to some sort of civics/philosophy style course. I don't think that's going to solve the problem that trying to redefine words out under people doesn't go very well though. It's not a logic problem, because logic relies on the definitions being agreed upon, and what you have here is one group trying to change the definitions in a way that makes everyone else wrong.
And then when scientists do invent new words so they don’t “redefine words out under people” they’re called snobs. Its why burning usually is talked about specifically as combustion if there’s any chance of confusion. For scientists it’s a damned if you do and damned if you don’t situation.
I just think theres room to be precise and I do think it has value. Trying to understand one another can be hard… miscommunication sometimes result in horrible results. And science education and communication to the lay person has been an unsolved problem since antiquity when then Library of Alexandria got burned down by an angry mob.
I still think we can all benefit from talking things over, trying to be open minded and having civil discussions like we’re doing right here. Communicating clearly never seems like a bad thing to me.
This isn’t a redox reaction though. Those are tin ions in equilibrium with each other.. so no combustion.
> I'll ask the chemists in the house if they know of any such reactions tomorrow since Google isn't being much use
I’d be interested what you find out, my chemistry knowledge has aged… theres always stuff I don’t know!
Edit: Yep you’re correct it is considered a redox, but not combustion.
I agree I wouldn't call this example combustion (which is typically required to be highly exothermic and therefore not easily reversible), but I believe it is a redox reaction. It's the transfer of electrons from one ion to another, which meets the definition I was taught.
Wikipedia seems to agree, both with my definition of redox reaction [1], and that this is one [2].
[1] https://en.wikipedia.org/wiki/Redox
[2] (See Introduction and History): https://en.wikipedia.org/wiki/Disproportionation
So they (two chemistry PhD students) both agree that it should be possible, but don't have any great examples. They point at disproponation as the right class of reactions (where I got Sn2+ from). They agree that the different ends of a hydrocarbon can react in a redox reaction, but at least for common chemicals it's usually a slow reaction.
For more combustion like examples what I got was "maybe look at peroxides" and "maybe caro's acid" (H2SO5).
I can't find anyone who actually managed to get Caro's acid outside of aqueous solution to explode it (in a reaction not involving water)... so I can't find anyone who is stating authoritatively what would happen if you managed to do so.
I can find plenty of explosive peroxides in literature, but haven't found any that are a simple redox reaction...
Anyways, I'm reasonably satisfied that it should in some sense be possible, even if not practical.
https://news.ycombinator.com/newsguidelines.html
>Eschew flamebait. Avoid unrelated controversies and generic tangents.
But who am I to throw water on your fire?
;)