Why is Carbon, the building block of life, safe when eating or drinking (carbonated water), but not when breathing (carbon monoxide or carbon dioxide)?


Why is Carbon, the building block of life, safe when eating or drinking (carbonated water), but not when breathing (carbon monoxide or carbon dioxide)?

In: Biology

Carbon in your blood is bad. When it enters your mouth, it goes into the stomach, through your intestines and out through your butt. Food doesbt ebter the blood stream.

The *element* carbon is a versatile atom that can build an endless number of *chemical* structures.

Those structures may be the massive and complex molecules we rely on, or they may be simple structures like carbon dioxide.

The wide variety of carbon-containing molecules may be helpful like sugars and fats, indifferent like diamonds and carbon dioxide, or dangerous like carbon monoxide and cyanide.

When you change the bonding structure, you change the properties.

H2O is critical for life. H2O2 will dissolve your bones.

The properties of a molecule are usually really different from its components’. For example, you need a molecule made of two oxygen atoms to survive (O2). But when there’s a third atom, it’s poisonous (O3).

Also, you can and do breathe CO2. The problem is inhaling ONLY CO2. Which is what kills you since you don’ get O2.

The key takeaway is that the way a molecule behaves is in no way predictable based only on the properties of the elements that compose it.

Carbon dioxide is what we exhale and it’s what carbonates soda. Take one of the oxygen from it, and it becomes Carbon Monoxide, a poisonous gas. There’s no way to have predicted that removing one oxygen turned a harmless inert gas into a deadly poison, other than having experimented and found out.

So it’s not carbon in particular that’s at the heart of the question, it’s the fact that the elements composing a molecule do not dictate the molecules behavior.

Breathing carbon is safe until it displaces enough oxygen to decrease pulmonary efficiency. Some degree of carbon dioxide is present is all the air we breathe. Carbon monoxide is particularly pernicious because of its ability to saturate hemoglobin more readily than oxygen.

Even oxygen can become toxic under pressures not experienced by the average person. Technical divers who work at depths beyond recreational scuba limits often use heavier nitrogen mix or even helium mixed gases to avoid oxygen toxicity. As with all things in life, balance is the key.

Lots of poisons are chemically “close enough” to another chemical that our body does use that they can make it into our bodies, but once they’re in they’re not chemically close enough to do the task they’re supposed to.

CO is one of these. It is chemically able to bind to hemoglobin, very well in fact. But when it gets to where our body wants to use it it’s not close enough to O2 for our bodies to metabolize it, and it’s not close enough to CO2 for the gas exchange in our lungs for our bodies to be able to easily remove it.

So a CO molecule sticks to the hemoglobin with no easy way to dislodge it, basically wiping out a red blood cell.

CO2 and especially CO bind to hemoglobin instead of oxygen and prevent your blood from carrying oxygen to the cells of the body. That’s bad.

The stuff in a carbonated beverage is CO2, there’s just not nearly enough of it to be harmful.

Carbon in most foods is in the form of some kind of hydrocarbon. It’s the raw material that your body uses to get energy. After we “burn” it , it turns into CO2

When you breathe your lungs take in oxygen (O2) and give out carbon dioxide (CO2). It’s like a merry go round where oxygen gets on and carbon dioxide gets off.

Carbon Dioxide is safe to breathe – it’s what you breathe out of your lungs constantly. It’s when the air has carbon dioxide and not enough oxygen (O2) that you have a problem breathing carbon dioxide.

Carbon Monoxide is a different level of toxin – again because your body wants and needs to take in oxygen, but the carbon monoxide binds to the receptors that want to take in the oxygen but don’t. To continue the merry go round metaphor, the carbon monoxide gets on the merry go round, then refuses to get off when it comes around again even if there’s oxygen waiting to get on.

Please, chemistry is so much more complicated than that. Even two incredibly complex molecules that are almost identical except for the tiniest difference can still function wildly differently.

Anyway, its good to drink water right? But it’s not so good to pour water into your lungs. Things function in a speicific way under specific conditions. Carbon is no exception to this. Meanwhile, carbon dioxide and carbon monoxide aren’t specifically toxic to life, but they displace oxygen and not having oxygen is always bad. Our air is 78% Nitrogen, but breathing in a higher percent can do the same thing. That doesn’t make nitrogen dangerous, and it also doesn’t make every compound containing nitrogen safe either.

ELI5: The properties of compounds/molecules can be COMPLETELY different than the properties of the element.

* Element: The basic building blocks of life, carbon, nitrogen, hydrogen.
* Molecule: Take multiple elements and put them together into something like CO2, CO, etc.

Elements and molecules have COMPLETELY different properties. An element inside of a molecule can be toxic, but because it’s in the molecule it’s perfectly safe.

ELI’m Older: Elements are made of atoms. Atoms are the basic building blocks of life. Atoms are made of protons, neutrons, and electrons. The NUMBER OF electrons determine an atom’s properties. It’s reactivity, how stable it is, etc. When two or more atoms come together to make a molecule, the electrons move around and change. Some move closer to one atom, some move away from another atom. This change makes the MOLECULE have completely different properties than the atom, TYPICALLY because when two or more atoms come together they do so because it’s more STABLE for them to hold onto each other than to be lone atoms. (SOME atoms are super dangerous/reactive because they WANT more electrons, some are super dangerous/reactive because they have TOO MANY electrons. When you pair an element from each of these two groups together, they become MUCH LESS reactive because the element with too many electrons gave it’s extra electrons to the element that wanted electrons.)

The best example I can think of is salt. Literally sodium chloride. Alone, both sodium and chloride are extraordinarily dangerous elements. Sodium explodes on contact with water, and chlorine forms chlorine gas which was used as a weapon of war. But TOGETHER, they form a nice stable, non reactive compound that we consume everyday. This is also why it’s not a huge deal when a seemingly dangerous element (say, mercury or arsenic or sulfur) is sometimes used in things that humans consume. So long as the molecule that contains that element is safe, it’s not an issue.

TL;DR: Molecules (made up of 2 or more atoms (elements)) have completely different properties than the atoms that they are made of due to changes in the position/number of electrons.