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“I have two water nmolecules right over here and typically the water molecules as they they interact with each other nthey form these hydrogen bonds that s due to the nof. The water molecule. We ve talked a lot about that they slide past each other these nhydrogen bonds give them all these neat properties of water. But chemistry is much nmessier than sometimes our diagrams or explanations show there s all sorts of crazy interactions.
All of these things are bumping into each other in all different ways and not only are the molecules bumping in different ways. But any given moment. The electrons are jumping around and on average they might spend more time they might spend more ntime around the oxygen forming a partially nnegative charge at that end. And then a partially positive charge near the hydrogens.
Because the nhydrogens are having their electrons hogged away from them in fact. This is what nforms the hydrogen bonds. But there s always nconstantly change. There because they re all just jumping around it s all very probabilistic and so you can imagine under njust.
The right conditions. One oxygen or one water nmolecule might just graze this water molecule nin. The right way that these electrons nthat. These electrons get close enough to nab nto nab this hydrogen.
But it doesn t nab the entire hydrogen. It doesn t nab the nnucleus and the electron and a typical hydrogen atom na. Typical hydrogen atom. Actually let me draw it a typical hydrogen atom is just a proton is just a proton in the nucleus actually the most typical nisotope of hydrogen has no neutron.
So it s just na proton in the nucleus and an electron orbiting around it so this right over here is positive actually maybe i ll draw it that way you have a positive nproton and then you have a negative electron you nhave a negative electron orbiting around it actually it s more of a orbital so it s really this electron nis jumping all around it but you could imagine nthese electrons in this covalent bond. They were already being these we already being hogged these were already being nhogged by this oxygen in fact that s what was forming this partial negative charge over here and the partial positive charge over here. So these would be attracted to this partial positive charge. Remember there you nhave a partial negative charge over here.
This is nactually. What s forming the hydrogen bond and it actually could bond nto. The hydrogen proton while both of these nelectrons including one of these electrons that used to be part of this hydrogen or you could consider used to be part of that hydrogen are nabbed are nabbed by this oxygen and in this circumstance nand. I m not saying that this happens all the time but under just the right conditions this actually can happen nand.
What would result so..
Let me what result is this thing over here instead of just being a neutral water molecule would look like this so you have your oxygen. You have not only your two hydrogens now you now have a third hydrogen. You now have a third hydrogen. So you have these two covalent bonds these.
Two covalent bonds. This lone pair and now this lone pair nwhich. I have circled in blue is now being shared with nthis hydrogen proton. This electron right over nhere of the hydrogen got nabbed by this oxygen.
So now you ve formed nanother covalent bond and now this character over here. He s lost the hydrogen proton. But he s kept all of the electrons so this character over nhere s gonna look like this you re gonna have your oxygen. And now.
It s only going to only be bonded to one hydrogen. Only nbonded to one hydrogen has these two original lone pairs. These two original lone npairs right over here. And then took both of the electrons from this covalent bond.
And took both of the electrons nfrom. This covalent bond and so it has another lone pair. So this molecule gained just a proton without getting any electrons. So.
If you do that you re nnow. Going to have a net positive charge nfor. This one over here and this molecule over nhere actually let me let me ugh let me just write it i wanna write. It a little bit neater and this molecule over here.
So we have this molecule. Plus. This one this one lost a proton without any other changes. So it now has a negative charge.
So just like that you nwent from two neutral water molecules to two ions and these ions this one over here the one on the left..
The one that is now h. Three o h. Three o h. Three o and it now has a positive charge positive charge actually i put that o in a different color h.
Three h. Three o. It s a positive charge this nis called the hydronium hydronium and this one over. Here.
That is oh minus. So. It s oh o. Let.
Me nget. The colors right oh minus. This is called the n. It s negative you can njust call.
It an i ll just write. Hydroxide ion right over there. So you have this water nand. It s just kind of automatically under the nright circumstances.
This isn t happening a lot. But under the right circumstances you could have one of the water molecules nabbing just the hydrogen proton from nanother water molecule and that water molecule nis gonna keep both of the electrons and then they ionize they have autoionized nand this phenomenon. This is called let me write that down nit s a nice big word autoionization autoionization of of water. And i really want to make nit clear.
What happens this hydrogen over here nthat you can imagine at first was a proton and an electron. The typical isotope of hydrogen. Actually does not have a neutron. But then this electron got swiped.
This electron this electron nwas part of this bond..
And it gets swiped away. And so all you re left is with this proton and this proton goes to this other water molecule giving that a positive charge and so you might say n well the concentration nlet me actually draw a little tub of water nhere let s say this is a liter of water this is a liter. This is a liter of water the concentration of nhydronium in typical water. The concentration of h.
Three o. The concentration of h. Nthree o. In typical water and you put brackets around something to denote one times ten to the negative seven molar and molar this just nmeans.
This is the same thing as one times ten to the negative seven moles moles per liter. And now you might be saying n. Well i encourage you to watch the video on what a mole is but a mole is a quantity. It s like saying.
But it s a much larger. A dozen is equal to 12 of something. A mole is roughly equal. Nto let me write it a mole is approximately equal to 602 times.
Ten to the 23rd ten to the 23rd of something and you re typically ntalking about. Molecules a mole of a substance means approximately 6022. It actually keeps going times. Ten to the 23rd molecules of that thing.
So you might say let me actually let me write it down one times. Ten to the negative seven moles per liter times times. I ll do it this way times six. I ll just go nwith six since we re gonna go approximately.
So approximately six ntimes ten to the 23rd six times. 23rd molecules nmolecules per mole molecules per mole well these two would cancel out and you would nmultiply these two numbers you would get six times. Let s see ten to the negtive seven ntimes ten to the 23rd that s still gonna be nten to the 16th power molecules per liter molecules per liter so nyour first reaction is but we have to remind ourselves there s just a lot of molecules nof water in there as well in fact a liter of water is roughly. So one liter of h.
Two o..
Contains contains approximately 56 56. Moles. Moles of h. Two o.
So one way to think about it is thinking about a liter of water. I have i ll do it over here so if you look at this ratio. Nthen you start to appreciate the ratio of one times. Ten nto.
The negative seven to 56 let me do it down here. So this is the same thing as one times. Ten to the negative seven to 56. Is the same thing as nlet s just multiply both side times or the numerator nand.
The denominator times. Ten to the seventh. So if we do that this nis. The same thing as one one the ratio of nhydronium to regular water to h.
Two o is gonna be one nto let s see if i multiply 56 times ten to the nseventh. I m gonna have five let me get write nin that same color. I m gonna have five six nthen. I m gonna have i m gonna throw seven nzeros at the end of it let me do that one two three four five six seven.
So the ratio of hydronium nto regular h. Two o is one for ever five nhundred and sixty million. So even though you might nsay for every one of them you actually have roughly five hundred sixty nmillion molecules of h two o. So that should give you nan appreciation for the fact that this isn t that typical in fact you re gonna nsee this much more often than you see this over here in fact if you wanted nto make these arrows kind of show which direction nthe equilibrium sits in it s actually much further nit s actually much further to the left so we could make this arrow much bigger.
But it also gives you an appreciation for just how many nmolecules you have sitting. ” ..
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