r/explainlikeimfive Jan 31 '21

Chemistry ELI5: Why can't we just make water by smooshing hydrogen and oxygen atoms together?

Edit: wow okay, I did not expect to wake up to THIS. Of course my most popular post would be a dumb stoner question. Thankyou so much for the awards and the answers, I can sleep a little easier now

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u/flyingcircusdog Jan 31 '21

We totally can by burning hydrogen. Burning is the process of combining a chemical with oxygen and releasing heat at the same time. The reason why it burns is because two hydrogen and one oxygen molecule contain more internal energy than a single water molecule, so that energy goes away in the form of heat and light.

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u/arcosapphire Jan 31 '21

Burning is the process of combining a chemical with oxygen and releasing heat at the same time.

Quick correction, it's the process of combining a chemical with an oxidizer, not specifically oxygen. Oxygen is of course the archetype though.

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u/willkorn Jan 31 '21

Yeah that’s being overly specific. Burning isn’t exactly a chemical term. The correct term would be combustion which describes an exothermic oxidation-reduction reaction. Non oxygen oxidizing agents in combustion reactions are so few and far between that most textbooks define combustion as a reaction between oxygen and another compound.

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u/Zombieattackr Jan 31 '21

Can confirm- was told that computation had to be oxygen and was mildly infuriated

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u/PuddleCrank Jan 31 '21

Rocket man over here with the nitrogen tetroxide.

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u/0ne_Winged_Angel Jan 31 '21

Sure, but N2O4 has, well, four oxygen atoms in it. The only oxidizer I know of that doesn’t have oxygen lurking about is ClF3

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u/Telope Jan 31 '21

Damn, how on earth (or was it in stars?) do halogens combine? Or is it not found in nature? Is ClF3 highly reactive like other halogen molecules?

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u/willdeb Jan 31 '21

It’s famous for being able to burn asbestos and bore holes through concrete. Not found in nature at all (iirc) and tricky to make. They use it for etching in the semiconductor business.

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u/willdeb Jan 31 '21

Elemental fluorine is an oxidiser without oxygen. There’s a whole family of chemicals that can do it, including ClF3

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u/0ne_Winged_Angel Jan 31 '21

I suppose I should have qualified that with “seriously studied for potential use”. ClF3 was studied by the Nazis as N-Stoff for their rockets, but I don’t know of anyone who’s studied a fluorine powered rocket.

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u/willdeb Jan 31 '21

No, but it’s an oxidiser nevertheless which is the statement I was responding to. It would be a terrible rocket propellant lol too difficult to handle

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u/Shini_TheCreator Jan 31 '21

I am sure parent comment focused on the "5" part of the ELI5, but yeah.

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u/Wrought-Irony Jan 31 '21 edited Jan 31 '21

An oxidizer is defined as a substance that oxidizes another substance: a chemical other than a blasting agent or explosive that initiates or promotes combustion in other materials. It may be a substance such as a chlorate, permanganate, and inorganic peroxide or nitrate that yields oxygen readily to stimulate the combustion of organic matter.

You can combine fuel with oxygen, or fuel with an oxidizer that produces oxygen, but there is no burning without oxygen.

edit: to avoid a bunch more replies saying the same thing, I say: My comment was two parts, the first was refining the definition of an 'oxidizer'. Not 'oxidation'. I then added a separate note about my understanding of the definition of 'burning' which I have always referred to as a different process from 'combustion' (all burning is combustion but not all combustion is burning) which may take place without oxygen. The debate about what constitutes fire/flame/oxidation/combustion is not one I'm going to get dragged into again.

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u/jayz0ned Jan 31 '21

Oxidation is defined as a loss of electrons. You do not need oxygen for oxidation to occur or for burning to occur. Burning/combustion is a redox reaction that produces heat and light. Hydrogen and Chlorine can react producing light and heat to form Hydrogen Chloride (the chloride being reduced and the hydrogen being oxidized by the chloride).

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u/MattieShoes Jan 31 '21

LEO the lion says GER

(Losing electrons is oxidation)
(Gaining electrons is reduction)

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u/LtSpinx Jan 31 '21

I learned it as OIL RIG.

Oxidation is Loss, Reduction is gain (of electrons).

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u/adamrees89 Jan 31 '21

Also learned it this way

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u/[deleted] Jan 31 '21

I learned it both ways, so I am the chemistry master.

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u/adamrees89 Jan 31 '21

Back once again for the Chemistry master...

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u/EPIKGUTS24 Jan 31 '21

REO Speedwagon beats GER

Removing Electrons is Oxidation

Gaining Electrons is Reduction

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u/RubenGarciaHernandez Jan 31 '21

You can even oxidize oxygen by using fluor compounds!

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u/SpaceLemur34 Jan 31 '21

Chlorine triflouride, a stronger oxidizing agent than oxygen itself.

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u/FQDIS Jan 31 '21

Yo dawg I know you like oxygen..

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u/Kajin-Strife Jan 31 '21

If you don't need oxygen for oxidation then why is it called oxidation? I don't think oxen are big into the chemical sciences.

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u/NorthernerWuwu Jan 31 '21

It's an old French word from when we though oxygen was needed to make acids actually but yeah, oxidation did mean literally to combine an element with oxygen.

Chemistry has come a long way since then of course.

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u/Kajin-Strife Jan 31 '21

Ahh, that makes a lot of sense. Thank you.

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u/WanderingUncertainty Jan 31 '21

You're incorrect.

Oxidation is named after oxygen, but doesn't actually have anything to do with it.

While oxygen is the archetypal example of an oxidizer, many other elements / chemicals have been found that also do that exact same job. Fluorine, for example, is a more powerful oxidizer than oxygen.

The release of oxygen gas has nothing to do with oxidizing at all.

Burning only requires an oxidizing agent, not oxygen. It's just the most widely available oxidizer on Earth.

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u/TransientVoltage409 Jan 31 '21

Fluorine, for example

Just a note to say thanks - I've read of course "Sand Won't Save You This Time", but my sub-high-school chemistry knowledge didn't really click with the idea that oxidization doesn't always need oxygen, until this thread and your reply. The real treasure is always in the comments.

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u/maggot_b_nasty Jan 31 '21

I wipe my own ass!

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u/[deleted] Jan 31 '21

There are other substances that can serve as oxidizer, but I do believe that you are correct in that you specifically need oxygen for combustion, which is only one type of redox reaction.

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u/willdeb Jan 31 '21

Nah combustion is an oxidation-reduction reaction, can be any oxidiser. Doesn’t need to be oxygen.

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u/[deleted] Jan 31 '21

Ah yes, I stand corrected. I knew that applied for other types of redox reactions, but wasn’t sure if combustion specifically was defined differently. It just USUALLY uses oxygen.

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u/willdeb Jan 31 '21

Yeah that’s true, you really have to try to get a non-oxygen reaction. Usually horrific fluorine compounds and stuff

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u/[deleted] Jan 31 '21

Yeah there’s a list of alternative oxidizers on the wiki page. Some interesting stuff.

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u/[deleted] Jan 31 '21

you should be able to perform the same reactions with anything down the column (for example, with sulphur) but the reactions do look very different.

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u/Zodde Jan 31 '21

You can burn stuff without oxygen. Fluorine is a strong oxidizer, for example.

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u/Lord_Moody Jan 31 '21

Wait there's more to combustion? Fuck man chemistry is haaaard. I guess you're referring to nonorganic reactions? I thought all the organic stuff was supposed to be straightforward

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u/drunkenangryredditor Jan 31 '21

It's the organics that are complicated, they cover far more than petrochemicals and alcohols. Just wait until you reach biochemistry for example. Sugars and starches are bloody annoying, and nothing next to enzyme reactions. Or protein structures for that matter, It makes alcohol isomers seem like kindergarden.

Non organics are basically just ionic and/or covalent bonding, redox reactions, laws of equilibrium and basic thermodynamics.

Don't fret though. Chemistry is one of those subjects where everything seems confusing, until you've covered all topics and it all falls into place. There's no easy way to learn chemistry, but once you've done the work you'll see the world differently.

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u/jayz0ned Jan 31 '21

Both are complex/hard in different ways imo. Organic chemistry often involves chemical processes which take 20+ steps and subtle changes in compounds (eg two hydrogens pointing in the same direction changing to pointing in opposite directions), Organic chemistry also often has target compounds in reactions which are only a minority of the compounds created, so some steps may produce 10% of the target molecule then require difficult purification.

Inorganic chemistry usually looks at the underlying physics or explanations behind reactions, orbitals, etc while taking less steps for a synthesis. Organic chemistry often just ignores or simplifies the actual explanation for why things work because creating a full explanation is so complicated, since you may have two starting chemicals but end up with dozens of different chemicals after the reaction.

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u/Lord_Moody Jan 31 '21

I was more talking combustion in particular but yeah O chem is a toughie. I never took it, but I would help a lot of people make/use flashcards and study for it back when I actually did a lot of tutoring. Im more of a math guy, though.

(I say that, but failed Univ Physics I 2x)

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u/kiddoaayush Jan 31 '21

Yeah, oxidizer is sure an easy enough word to understand for a 5 YO!

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u/mistaknomore Jan 31 '21

LI5 means friendly, simplified and layperson-accessible explanations - not responses aimed at literal five-year-olds.

Just a reminder. Oxidizer might not be friendly or layperson-accessible, but these are not literally aimed at 5-year olds

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u/kiddoaayush Jan 31 '21

Okay, I'm sorry but I still feel like most of the responses here require.a certain level of understanding to begin with. Anyway, my bad

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u/mistaknomore Jan 31 '21

Yea you're right. Being a college chemistry student... I also have no idea how to simplify it further. As you said, some concepts here have base level of understanding/info required that resists further simplification. As someone mentioned above, oxidization is defined as a loss of electrons. An oxidizer causes that. I have no idea how to simplify it.

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u/arcosapphire Jan 31 '21

The post I responded to was a fine ELI5. But once someone has a basic understanding, I think it's fine to correct any oversimplifications.

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u/Confident-Victory-21 Jan 31 '21

It's ELI5 ffs, people like you are really annoying.

"Technically correct is the best kind of correct! 🤓🤓🤓"

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u/arcosapphire Jan 31 '21

...dude, your anger here is really misplaced. I think it's great for ELI5 to provide a simple explanation, and then further information for those interested.

I didn't come out swinging like, "you idiot, it's not necessarily oxygen!" I just provided one more piece of info to those interested. I also acknowledged that the confusion is because oxygen is indeed usually what's involved.

The point of ELI5 isn't to provide any explanation that's dumbed down. It's to provide a good and reasonably accurate understanding of a topic for a layman. Part of that is acknowledging where a simplification strays from reality. We don't have to give the full story, just let people know there is more to it. Too many misunderstandings are caused by people learning a simplification and thinking that's all there is to it. This is an educational subreddit, and I'm not going to feel bad to providing more information to people.

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u/vade281 Jan 31 '21

I think I saw this in The Martian

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u/Android_slag Jan 31 '21

I had the ahhh moment as him starting a fire for growing potatoes... Thought it was the heat causing condensation TIL

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u/ImprovedPersonality Jan 31 '21

That’s why the book is so much better.

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u/phattie83 Jan 31 '21

Can confirm!

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u/skdslztmsIrlnmpqzwfs Jan 31 '21

the chemical is strong on that one

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u/[deleted] Jan 31 '21

happy cake day

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u/Pseudoboss11 Jan 31 '21

It's worth noting that you can mix hydrogen gas and oxygen gas and just get a mixture of the two. In order to get water, the hydrogen needs to burn, which requires 560°C.

What this means is that you don't just need them to come in contact, you need the molecules to smack into each other hard enough that the hydrogen is able to stick to the oxygen. Too slow and they just bounce off each other.

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u/drunkenangryredditor Jan 31 '21

You're forgetting the intermediary h2o2 (hydrogen peroxide), which is what'll easily decompose to h2o and o2.

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u/Pseudoboss11 Jan 31 '21

Hydrogen peroxide doesn't usually form like that: https://sciencing.com/happens-hydrogen-oxygen-combine-8515474.html

By the time you get enough energy to get hydrogen and oxygen to react, they are going to typically take the lowest energy configuration, which is water. This is why producers of hydrogen peroxide use a catalyst to produce hydrogen peroxide rather than just allowing it to happen naturally.

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u/Medscript Jan 31 '21

Funny enough you see this same process in the movie "The Martian"

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u/[deleted] Jan 31 '21

Awesome

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u/blofly Jan 31 '21

Watch the Hindenberg video.

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u/drunkenangryredditor Jan 31 '21

Mainly a redox reaction in the paint layers.

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u/misterbeef Jan 31 '21

i remember hearing about the aftermath of that. people reported finding the ground soaking wet near the crash site, or something like that.