That's why the meme works. It's not because water autoionizes; it's because water is amphoteric, meaning it can act as either a Brønsted-Lowry acid or BL base depending on what what it's reacting with. Put water with ammonia, and water acts as an acid. Put water with acetic acid, and it acts as a base
I once brought up in a family dinner how incredible and strange water is, and how we don't really think about it.
It appears naturally in all three phases, expands when frozen, has a high surface tension, has a high specific heat, and can behave as a mild base or acid. Oh, and all the living stuff has water in it.
Nobody really understood what I meant except my sister.
If it makes you feel any better, I totally get it.
I’ve thought many times how different the universe would be (would complex life on earth even work the same way???) if frozen water became more dense and sank like most frozen substances.
Kinda, but not really. Deuterium exists naturally in more or less the ratio as it has since the solar system first coalesced.
Also, deuterium is a component of heavy water, but the term "deuterium" actually referred to the specific isotope of hydrogen where the nucleus consists of one proton and one neutron, as opposed to a single proton (which is the more common isotope)
Autoionization and the reverse reaction are constantly happening in water, and when the reaction is happening at the same rate forward and backward the system is said to be "at dynamic equilibrium" (aka, stuff is happening, but there's no net change)
In pure water, the equilibrium concentration of hydronium and hydroxide are equal, so it's said to be neutral. At room temperature, that equilibrium concentration is approximately 1*10^-7 moles per liter, which gives a pH of 7 (since pH is defined as the negative log _10 of hydronium concentration)
The dissociation constant of pure water at RT is 1x10^-14. This is many magnitudes more than just one per avogadros number. The "trick" is that any given molecule of water basically has that 1x10^-14 chance of being split or otherwise whole at any given time.
Well, yes and no. The pH scale follows the hydrogen ion concentration, but specifically in aqueous media. The reason 7 is in the "middle" of the scale is because the natural dissociation of water sits at equilibrium at 10^-7 M H+ at 298K, IIRC. So perturbations naturally just displace that specific equilibrium, so it absolutely is normative to water.
Interestingly enough, in other solvents a neutral pH is going to be a different value. IIRC, ammonia has an autoionization constant of 10^-30, so a neutral pH would be 15
By that definition, it can’t be exactly 7 then either. 10^-7 is just an estimate that we’ve agreed works fine. To my knowledge we haven’t really tried to improve this accuracy either?
The exact value varies with temperature, so it's a "good enough for the typical variations in temperature experienced by most aqueous solutions" estimate.
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Little bits of it oscillate between hydronium and hydroxide so a little of both but not enough to make a difference.
That's why the meme works. It's not because water autoionizes; it's because water is amphoteric, meaning it can act as either a Brønsted-Lowry acid or BL base depending on what what it's reacting with. Put water with ammonia, and water acts as an acid. Put water with acetic acid, and it acts as a base
Source: I teach college chemistry
Water is so cool. I like how the hydrophobic effects drives protein folding
I once brought up in a family dinner how incredible and strange water is, and how we don't really think about it.
It appears naturally in all three phases, expands when frozen, has a high surface tension, has a high specific heat, and can behave as a mild base or acid. Oh, and all the living stuff has water in it.
Nobody really understood what I meant except my sister.
Do you know about ortho/para-H
2O? It only gets weirder.Neat, I will be saving this and reading it when I'm less busy... maybe I'll get back to you on it.
If it makes you feel any better, I totally get it.
I’ve thought many times how different the universe would be (would complex life on earth even work the same way???) if frozen water became more dense and sank like most frozen substances.
Kinda, but not really. Deuterium exists naturally in more or less the ratio as it has since the solar system first coalesced.
Also, deuterium is a component of heavy water, but the term "deuterium" actually referred to the specific isotope of hydrogen where the nucleus consists of one proton and one neutron, as opposed to a single proton (which is the more common isotope)
Ah yes amphoteric compounds
Do you mean dihydrogen monoxide?
also known as hydric acid
Close, the standard IUPAC acid nomenclature would be "hydrohydroxic acid"
Pretty sure the OP meant hydrogen hydroxide.
H2O is neutral PH, and so answer is no. But then water tends to have a bunch of shit disolved in it. So answer is yes.
A self-contradicting proposition based on ambiguity of definition of water, of all things. This statement can be used to make HAL explode.
If you take into consideration the self-ionization of water, it's both, at the same time.
2 H
2O -> H3O^+^ + ^-^OHAFAIU, it doesn't change the PH neutrality.
I understand that they self combine/react again? But is that reaction still water?
Autoionization and the reverse reaction are constantly happening in water, and when the reaction is happening at the same rate forward and backward the system is said to be "at dynamic equilibrium" (aka, stuff is happening, but there's no net change)
In pure water, the equilibrium concentration of hydronium and hydroxide are equal, so it's said to be neutral. At room temperature, that equilibrium concentration is approximately 1*10^-7 moles per liter, which gives a pH of 7 (since pH is defined as the negative log _10 of hydronium concentration)
It's not neutral, pure water is slightly acidic due to free hydrogen
What is the PH of the water? 🤔
About 7. Fun fact i did not know before research, at 100 C waters pH can go as low as 6.14.
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/Acids_and_Bases_in_Aqueous_Solutions/The_pH_Scale/Temperature_Dependence_of_the_pH_of_pure_Water
Oh! So that's why hot water burns you!
I know it's a joke and all, but it's not just the pH that makes something burn. A regular coke has a pH of around 2.5, for example.
Oh yeah? Then explain the sensation my sphincter feels upon butt-chugging three cans of coke, smart guy?
I believe that's caused by the CO2, but I'd have to test to be sure, brb.
They still aren't back... Oh god, did you do 4 cans?! Everyone knows you can't do 4 cans!
Now you tell me?!
I don't know, I heard that coke can burn a hole in your septum
It is the final frontier for either, your meme could have been so much more interesting. SAD.
Is this about the anomaly of water? I vaguely remember it from school
No, this is about water being amphoteric compound meaning it behaves like a acid or base in different circumstances.
https://en.m.wikipedia.org/wiki/Amphoterism
A water molecule in aqueous solution. How can you tell it's being dissolved, or doing the dissolving?
In high school I was told that one in avagadros number of water molecules splits into ions.
Is that right? It seems like a very small amount.
The dissociation constant of pure water at RT is 1x10^-14. This is many magnitudes more than just one per avogadros number. The "trick" is that any given molecule of water basically has that 1x10^-14 chance of being split or otherwise whole at any given time.
Isn't water itself the pretty literal definition of 0 and it doesn't become one or the other until it's a solution with something else?
Water is the definition of 7.
Right, whatever the midpoint was. It's been a minute since my last chemistry class.
Also I’m pretty sure it’s only coincidentally 7. The calculation for pH isn’t based on any property of water.
Well, yes and no. The pH scale follows the hydrogen ion concentration, but specifically in aqueous media. The reason 7 is in the "middle" of the scale is because the natural dissociation of water sits at equilibrium at 10^-7 M H+ at 298K, IIRC. So perturbations naturally just displace that specific equilibrium, so it absolutely is normative to water.
Interestingly enough, in other solvents a neutral pH is going to be a different value. IIRC, ammonia has an autoionization constant of 10^-30, so a neutral pH would be 15
By that definition, it can’t be exactly 7 then either. 10^-7 is just an estimate that we’ve agreed works fine. To my knowledge we haven’t really tried to improve this accuracy either?
The exact value varies with temperature, so it's a "good enough for the typical variations in temperature experienced by most aqueous solutions" estimate.
But is it +0 or -0? Neutral 0 is a lie, a measurement precision error.