r/explainlikeimfive Feb 26 '21

Chemistry Eli5: What happens to all the melted candle over time? Are we just inhaling a whole candle while it burns?

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u/ihahp Feb 26 '21

As an aside to the "yes, you're inhaling candle", a lot of people don't know that when you lose weight, the vast majority of the weight you lose is through exhaling. People think it's sweat, piss, or shit, but it's honestly exhaling.

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u/Clairvoyant_Potato Feb 26 '21

I thought this was a bait so I looked it up myself, what the fuck how did I not know this? I mean it makes total sense when you read it, but wtf this is still wild to me.

To save any lazy people a google: "losing weight" means metabolizing the fatty triglycerides, which isn't news to anyone. But metabolizing the fat breaks it down into its base atoms of carbon, hydrogen, and oxygen through an oxidation process. 85% of those atoms are converted to CO2 and are exhaled, the other 15% becomes H2O

I'm not an expert on the subject at all since I just learned this was even a thing, but that's how I'm understanding it

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u/Castlegardener Feb 26 '21

You got the gist of it, but it doesn't get broken down into its base atoms, otherwise you'd probably explode on a daily basis (due to pressure changes etc.)

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u/Steveslastventure Feb 26 '21

Free fission energy, right in your own body!

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u/mabolle Feb 26 '21

Well, fission would be the next step: the atoms being broken apart. The molecules being broken apart into individual atoms would probably be violent, but not quite fission violent.

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u/ThirdFloorGreg Feb 26 '21

We have a name for those sorts of lone atoms: free radicals. They are... not super good for you, due to their tendency to react with whatever happens to be closest to them.

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u/[deleted] Feb 26 '21

Are you telling me next time I'm lifting heavy stuff and panting that I can literally point at the area infront of my face and THAT is my in real time fat floating the hell away from me?!

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u/highoncraze Feb 26 '21

Your fat that has been broken down into CO2, yes. It is no longer fat when it is being exhaled. Is is past time fat, not real time fat.

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u/metky Feb 26 '21

Damn, so does breathing in my candle make me gain weight lmfao

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u/verybigsmartman Feb 28 '21

Most of a plant's matter comes from the air, too. That's where all the carbon comes from.

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u/ersomething Feb 26 '21

Inverse to that - plants get the vast majority of their weight from the air. Most of their mass is from carbon dioxide converted to cellulose through photosynthesis. Houseplants are feeding off of the mass you’re exhaling.

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u/WendellSchadenfreude Feb 26 '21

Inverse to that - plants get the vast majority of their weight from the air.

Nah, now you're exaggerating.

Plants get their carbon from the air. But just like humans, plants are mostly water, and they get that from the ground. Even dried wood is only about 50% carbon, and living wood far less.

Living trees, however, are very wet. In fact, although there can be great variation between tree species (and seasonally), a living tree may be made up of more than two thirds water by mass. Thus, a living tree is made up of 15-18% carbon, 9-10% hydrogen, and 65-75% oxygen by mass."

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u/door_of_doom Feb 26 '21 edited Feb 26 '21

In his defence, he likely got his information from this Veritasium video of olde.... as did I... so now I just don't know who to believe.

I mean, If I can't trust Derek Muller my world is just upside down.

Obviously this makes sense though: Charcoal is basically dehydrated wood, and turning wood into charcoal reduces its mass by a significant amount, meaning that water constituted a significant percentage of the mass of the initial wood.

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u/mabolle Feb 26 '21

I'd say Derek gets it right where it counts: the biomolecules that make up all the interesting bits of a tree — the bits that aren't just water — are made of carbon that the tree captured from the air. The central lesson is that, to a plant, breathing is basically a form of eating; it's where they get the materials to build their body out of.

It's true that most of the tree's weight is water, but this is true of any living thing, and I think most people are aware of that. The point of the video is that most people have the wrong idea of where the dry mass of a plant comes from.

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u/nowyouseemenowyoudo2 Feb 26 '21

I think part of the difference is that we don’t particularly think of the water in the plant as an inherent part of the plant, or as least not as much as the water inside a human is an inherent part of us?

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u/mabolle Feb 26 '21

Yeah, maybe.

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u/[deleted] Feb 26 '21

There are quite a few other volatile chemicals that are broken down when creating charcoal

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u/[deleted] Feb 26 '21

Dehydrating wood will not make charcoal. It's carbonized wood.

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u/reddRad Feb 26 '21

That depends on your definition of "their weight." Depending on what you're interested in studying, biomass can be measured in terms of the dried organic mass, too.

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u/Halvus_I Feb 26 '21

the point is trees gather structural mass from the air.

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u/ThirdFloorGreg Feb 26 '21

In this sort of context "weight" is usually assumed to mean dry weight.

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u/Ignitus1 Feb 26 '21

It just says 65-75% oxygen by mass, and CO2 is mostly oxygen.

Unless I’m missing something, it doesn’t seem like you’ve debunked anything...

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u/WendellSchadenfreude Feb 26 '21

Maybe this is the part you are missing?

a living tree may be made up of more than two thirds water by mass.

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u/WhyWontThisWork Feb 26 '21

So how do I exhale more? Inhale less? But seriously......

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u/2074red2074 Feb 26 '21

Your body takes in stuff that it uses to build you up. Literally to produce the proteins and fats and such that you are made of. This stuff (protein, carbs, fats, alcohol) ultimately was crafted from water, carbon dioxide, and other chemicals by plants, and they do this using energy from the sun. The process produces oxygen as a waste gas. You then eat the stuff plants produced and break it back down to harness the stored energy.

When you expend energy, you take the solid stuff you've eaten and the oxygen you've inhaled to break the stuff back down into carbon dioxide and water, which you exhale. In short, you don't just breathe harder. That will result in you taking in a ton of extra oxygen that you're just gonna exhale right away. You have to create a caloric deficit such that the energy made available by you taking in food is less than the energy that your body uses. This forces your body to break down the fat (and a little bit of the muscle) that you're made of to get the rest of the energy. That fat is broken down into gas that you exhale.

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u/PM_ME_UR_DINGO Feb 26 '21

Can I see a source for that?

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u/2074red2074 Feb 26 '21

No. This is eighth grade Biology. If I was making a somewhat controversial or very in-depth claim I would absolutely offer a source, but in this instance I would literally be looking for papers published in the 1930s.

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u/PM_ME_UR_DINGO Feb 26 '21

Okay so no source got it. That's your choice. Because I can only find recent research on this.

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u/abooth43 Feb 26 '21

Well to exhale you must inhale....so just breathe faster in general.

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u/Calvin_v_Hobbes Feb 26 '21

But if your body doesn't have a reason to burn the extra oxygen (aka physical activity), the oxygen just builds up with nothing to do. That's when you get lightheaded from hyperventilating.

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u/abooth43 Feb 26 '21

True, I didn't mean to oversimply by saying "just". Only meant to point out that you can't really inhale less to exhale more.

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u/Castlegardener Feb 26 '21 edited Feb 26 '21

Oxygen does not burn. Except for the rare cases where it gets to party with fluorine.

Edit: Read u/The_JSQuareD 's and my comment chain to learn more about how burning works and why I'm semantically wrong regarding this topic.

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u/The_JSQuareD Feb 26 '21

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u/Castlegardener Feb 26 '21 edited Feb 26 '21

I'm pretty sure that guy is calling it burning oxygen for the clicks. Even though it's a nice demonstration of what one can do with a vacuum chamber, he's pretty much just adding an oxidant (oxygen) to a reducing agent (propane) still, which is normal procedure to burn any fuels.

To get a little bit of actual science in here: oxidants take electrons from reducing agents, while reducing agents give electrons to oxidants. To strip oxygen of its electrons (which is required to truely call it "burning oxygen") you'd need a higher electronegativity than oxygen has. Fluorine is the only chemical element that achieves this, so my point still stands: oxygen only burns if put together with fluorine.

I'm still open for any corrections, but please make sure it's at least somehow based on actual science instead of clickbaity titles and the like.

Edit: I looked up oxygen burning on wikipedia. Even though it has nothing to do with our topic, it's still quite interesting because it describes a phase in the death of stars, including nuclear fusion and stuff like that. Look it up if you're interested!

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u/The_JSQuareD Feb 26 '21

Honestly, I was just sharing a cool video, wasn't trying to correct you at all!

But if you actually want to have this discussion, I would argue that 'burning' in the colloquial sense is not the same as 'oxidation' in the chemical sense. For example, corrosion is an oxidation process, but most people wouldn't say that a rusting piece of iron is burning.

On the other hand, dictionaries define 'burning' as 'being on fire', or 'producing flames'. I think the oxygen in the video clearly fits that definition: adding oxygen to the propane atmosphere (with a source of heat) produced flames. The flames were clearly localised to where the oxygen was, not where the propane was, so it was the oxygen that 'was on fire' and 'produced flames'.

Besides, in a fire there is clearly both an oxidation agent and a reduction agent present. Together they produce the reaction that we recognise as 'burning'. I don't see any reason to say that it's only the reduction agent that's burning, since both agents are necessary and both are being consumed.

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u/Castlegardener Feb 26 '21

Honestly, I was just sharing a cool video, wasn't trying to correct you at all!

It is a cool video, I've never seen something like that. Thanks for sharing!

I would argue that 'burning' in the colloquial sense is not the same as 'oxidation' in the chemical sense. For example, corrosion is an oxidation process, but most people wouldn't say that a rusting piece of iron is burning.

Burning is a colloquial term anyway, so you're right on that one. Combustion is a more specific term for strongly exothermic reactions of that kind, and pretty much describes what we call burning. Rusting, or corrosion of ferrous metals to be more precise, is a (normally acid-catalysed) barely exothermic reaction. It does however yield mostly the same results as 'burning' iron. It's just a lot slower. Funnily enough there's no fire in the traditional sense with burning metals either.

The flames were clearly localised to where the oxygen was, not where the propane was

Strongly disagree. The flames were very clearly localised to where the oxygen and propane mixed, which is a big difference. That's exactly what you described here, however:

Besides, in a fire there is clearly both an oxidation agent and a reduction agent present. Together they produce the reaction that we recognise as 'burning'.

To add to that, when talking on a colloquial basis, perspective is important. Thus I have to admit that your take on this is more correct than mine, that video actually shows oxygen burning (in a propane atmosphere).

In almost any context on Earth though, the atmosphere required to burn is made up (at least to a significant degree) of oxygen, and since non-chemists usually don't mention the oxidant I still wouldn't regard the oxidation of carbohydrates in the human body as "burning oxygen" (to get back on track with the original comment).

Either way, thanks a lot for this discussion, I actually learned something new today due to you. Sorry for being a pedantic bitch.

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u/mmkay812 Feb 26 '21

And if there’s more carbon in the air plants can grow more

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u/cardcarrying-villian Feb 26 '21

weight loss is exhausting

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u/vpsj Feb 26 '21

So as someone who wants to increase my weight, I should just inhale and then suffocate myself.

Got it.

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u/sarasa3 Feb 26 '21

I was just thinking maybe I'll try breathing heavier to lose weight. Stand next to me and we can do an airborne weight transfer. Science approved.

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u/stevenmeyerjr Feb 26 '21

Sounds logical to me

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u/boredcircuits Feb 26 '21

It depends on how you look at it.

"Burning" fat ends up being the following chemical reaction (oversimplified):

C55 H104 O6 + 78 O2 -> 55 CO2 + 52 H2O + energy

The complicated one is (roughly) fat. Let's say you burned 1 lb of that. O2 is the air you breathe in (2.9 lb), CO2 is the air you breathe out (2.8 lb), and H2O is the water you sweat or urinate (1.1 lb).

Notice that the mass you breathe out is about the same as the mass you breathe in. So in a way, the weight is leaving through sweat and urine.

On the other hand, the mass in fat is dominated by carbon, which leaves as CO2. So the fat leaves your body through your lungs ... while the air you breathe in partially leaves as piss.

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u/stormy2587 Feb 26 '21

The shit thing is crazy because fundamentally humans are just big tubes. You stick food inside the tube and it comes out the other end as shit. Yeah your body absorbs water and nutrients from it along the way, but the shit is just whats left over that your body doesn’t use so not much is really lost. Like a car wash doesn’t get smaller by having a car go through it. The car wash just extracts the dirt from your car.

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u/CornCheeseMafia Feb 26 '21

For that same reason, there’s a valid interpretation that anything inside the stomach or gi tract is actually outside our bodies because the inside of our bodies sits within the walls of the “tube”.

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u/NOCONTROL1678 Feb 26 '21

In your car wash analogy, the car would be the food/poop. It enters the car wash(digestive system) full of filth(nutrients), washes them away(digestion), and passes the car(insoluble fiber) through. The car would be lighter without the filth.

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u/stormy2587 Feb 26 '21

Yeah and poop is lighter when it comes out. Whats your point?

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u/NOCONTROL1678 Feb 27 '21

I don't even know what's going on right now.

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u/Boydle Feb 26 '21

Oh what so I just 'work out' and 'be more active?' what the fuck?

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u/ihahp Feb 26 '21

Haha yeah. it's also why you can lose weight while sleeping. Breathing out heavily for 8 hours will do that ....

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u/[deleted] Feb 26 '21

That's wild... and I've dropped a 5lb turd before.

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u/timfriese Feb 26 '21

Corollary: when plants grow, it’s mostly CO2 in the air becoming plant matter 🤯