• humanspiral@lemmy.ca
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    1 day ago

    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.

    • MunkyNutts@lemmy.world
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      1 day ago

      If you take into consideration the self-ionization of water, it’s both, at the same time.

      2 H2O -> H3O+ + -OH

      • humanspiral@lemmy.ca
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        1 day ago

        AFAIU, it doesn’t change the PH neutrality.

        I understand that they self combine/react again? But is that reaction still water?

        • NielsBohron@lemmy.world
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          1 day ago

          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)

  • Geodad@lemm.ee
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    2 days ago

    Considering that water autoionizes, yes - it is both an acid and a base.

  • Someonelol@lemmy.dbzer0.com
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    2 days ago

    Little bits of it oscillate between hydronium and hydroxide so a little of both but not enough to make a difference.

    • NielsBohron@lemmy.world
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      2 days ago

      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

        • TheOakTree@lemm.ee
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          2 days ago

          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.

          • SolarMonkey@slrpnk.net
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            9 hours ago

            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.

            • TheOakTree@lemm.ee
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              5 hours ago

              Neat, I will be saving this and reading it when I’m less busy… maybe I’ll get back to you on it.

      • NielsBohron@lemmy.world
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        1 day ago

        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)

  • lugal@sopuli.xyz
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    2 days ago

    Is this about the anomaly of water? I vaguely remember it from school

      • barsoap@lemm.ee
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        2 days ago

        The water molecule is amphoteric in aqueous solution

        A water molecule in aqueous solution. How can you tell it’s being dissolved, or doing the dissolving?

        • dustycups@aussie.zone
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          2 days ago

          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.

          • phdepressed@sh.itjust.works
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            2 days ago

            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.

  • 21Cabbage@lemmynsfw.com
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    2 days ago

    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?

      • CookieOfFortune@lemmy.world
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        2 days ago

        Also I’m pretty sure it’s only coincidentally 7. The calculation for pH isn’t based on any property of water.

        • wolframhydroxide@sh.itjust.works
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          2 days ago

          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.

          • NielsBohron@lemmy.world
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            2 days ago

            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

          • CookieOfFortune@lemmy.world
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            2 days ago

            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?