veerenyadav
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Solute for Metal oxides
Is there any solute which can dissolve metal oxides ( Fe2O3,MOx, etc) but not as ions ?
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j_sum1
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I think the word you want is solvent.
Yes. Water is pretty good. you can dissolve Na2O and K2O in water pretty easily.
But I suspect that is not the answer you were after.
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veerenyadav
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Both your points are correct. I am searching for a solvent and but it should not dissolve the oxide in the form of ions rather molecules .
Thanks
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j_sum1
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Well your problem right there is that most metal oxides are not molecular. There are exceptions. Osmium tetroxide springs to mind.
Let's think electronegativities here. Oxygen is the second most electronegative element. And metals are by definition those elements that are less
electronegative. Forming a bond between them is therefore going to involve a large difference in electronegativities which, again by definition,
means you are generally going to referring to an ionic bond rather than a covalent bond. And with ionic bonds you are going to get an ionic lattice
and dissociation into ions when dissolved. You are not going to get molecules.
Of course there are exceptions. (Aren't there always?) For example the OsO4 I mentioned before. But in general your answer is going to be No.
Metal oxides do not dissolve in anything in a molecular form.
Curious. What inspired this question? It strikes me as a weird one.
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DraconicAcid
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Since these oxides are not molecular, it will not happen.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Harristotle
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I disagree.
Iron oxides/hydroxides are frequently polymers, and the oxo-iron-oxo bonds are more covalent than ionic in nature. EXAFS and other studies have shown
this. Acid will depolymeris/ionise them to ionic form, but at high pH they are definitely not ionic..
Apparently there are other metals like this also. I don't have my old texts, but I recall xray diffraction photos of iron oxide as forming rings, not
spots - no regularity to that lattice!
Admittedly, the iron oxide was ferrihydrite from the protein ferritin.
This is suggested by this paper http://pubs.acs.org/doi/abs/10.1021/la00013a046 , the first that I lazily found. I was supprised to see Cr and Al mentioned as other suspects too.
Cheers, H.
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Eddygp
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Molecular or not, the thing is, except for osmium tetroxide, there is no single molecule of "Fe2O3", it is a reduction of the stoichiometric
proportion of atoms in the crystal. The problem is that it is a crystal.
In the same way as you can't dissolve high-density polyethylene in hexane in spite of it being basically the same thing, this is even more pronounced
for metal oxides. The whole lump kind of is "the" molecule. SOlvation cannot break the crystal apart (and if it did at all, it would be some kind of
hydrated iron complex, and certainly only in the presence of an anion from an acid or something).
there may be bugs in gfind
[ˌɛdidʒiˈpiː] IPA pronunciation for my Username |
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kmno4
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The answer is : ionic liquids.
Many 'insoluble' oxides (CuO, Fe2O3, Cr2O3, Al2O3, MnO2....) are soluble in such solvents.
As far as I remeber, adequate article was mentioned (or posted) somewhere on the board.
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Dan Vizine
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Soluble has different connotations depending upon what your intention is. For example, what is called soluble for spectroscopic purposes is not always
what you'd call soluble for preparative purposes. If you're trying for a very high solubility, or even a moderate one, it's not going to happen with
most of these oxides.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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DraconicAcid
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Quote: Originally posted by kmno4  | The answer is : ionic liquids.
Many 'insoluble' oxides (CuO, Fe2O3, Cr2O3, Al2O3, MnO2....) are soluble in such solvents.
As far as I remeber, adequate article was mentioned (or posted) somewhere on the board. |
Choline chloride-based ionic liquids will dissolve such oxides, but not as molecules.
The only time you'll get molecules of a metal oxide is when the metal is in a very high oxidation state- CrO3, Mn2O7, OsO4. For things like Fe2O3,
Al2O3, MnO2, etc, the bonding is network covalent. The bonds are covalent, but you don't have individual molecules. you have one massive
macromolecule instead, and the only way to dissolve it is to rip it into bits, effectively ionizing it.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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veerenyadav
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Does it mean polymeric oxides ......
Thanks for putting wonderful perspectives.
(A) Does it mean that polymeric oxides ( Si, Ca, Na,... ) can be dissolved in a solvent ?
(B) Can these oxides dissolve in the from of nano particles ?
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violet sin
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- veerenyadav
" it should not dissolve the oxide in the form of ions rather molecules ."
- J_sum1
- "Well your problem right there is that most metal oxides are not molecular"
- DraconicAcid
- "Choline chloride-based ionic liquids will dissolve such oxides, but not as molecules"
____________
I losely use DES /IC interchangeably below, DEEP eutectic solvent and ionic liquid, referring to a non-standard solvent. Also not citing specific
examples so I hope it's not to incorrect .
____________
It doesn't dissolve them as Fe +++ and O - -, but it doesn't necessarily dissolve them as the empiracle formula either.
the metal oxides would be dissolved in a manner similar to soap and grime, no? Correct me if I'm wrong, personally I saw it as an encapsulation by
units of a charged or electronic nature, affecting things like lone pairs and disrupting bonds that are normally favored. promoting solovation by
making the aggregate unit cluster( metal oxide/ionic liquid/DES sheath) more favored than a solid complex of oxide. More of a masking the electronic
nature of the units from one another and moderating the difference between dissolved substance and neat solvent. There would be a point at which the
disguise could no longer fool the solid or solution based on size.
If the attraction was as that, dissolved unit complexes could be "watered down" with extra ionic liquid to ensure total dissolution on a level
determined by geometry of the charge at an atomic scale. Something on the order of small numbers of metal oxide unit conglomerates are easily
envisioned, surrounded by the moderating cloak of bound and associated DES(deep eutectic solvent) which may not have the ability to separate more
fully. Or perhaps it goes all the way down to metal oxide units for some. Don't know. But *I bet* it would be safe to say they *could be on nano
scale before solvent could no longer peel bits off and hide them effectively. Safer to say the bits are very small if not empirical .
For reference
"Nanoparticles are particles between 1 and 100 nanometers in size"
https://en.m.wikipedia.org/wiki/Nanoparticle
Wiki
"The thing is, atoms are very, very small, but they still have a finite size. A hydrogen atom, for example, is about 0.1 nanometers, and a caesium
atom is around 0.3nm "
https://www.extremetech.com/computing/97469-is-14nm-the-end-...
-Is 14nm the end of the road for silicon chips?
__________________
This looks interesting, and maybe worth chasing down...
____
http://pubs.acs.org/doi/abs/10.1021/jp0642995?journalCode=jp...
==Task-Specific Ionic Liquid for Solubilizing Metal Oxides
"Protonated betaine bis(trifluoromethylsulfonyl)imide is an ionic liquid with the ability to dissolve large quantities of metal oxides. This
metal-solubilizing power is selective. Soluble are oxides of the trivalent rare earths, uranium(VI) oxide, zinc(II) oxide, cadmium(II) oxide,
mercury(II) oxide, nickel(II) oxide, copper(II) oxide, palladium(II) oxide, lead(II) oxide, manganese(II) oxide, and silver(I) oxide. Insoluble or
very poorly soluble are iron(III), manganese(IV), and cobalt oxides, as well as aluminum oxide and silicon dioxide. The metals can be stripped from
the ionic liquid by treatment of the ionic liquid with an acidic aqueous solution."
_________
http://pubs.acs.org/doi/abs/10.1021/je060038c
==Solubility of Metal Oxides in Deep Eutectic Solvents Based on Choline Chloride
"The solubility of 17 commonly available metal oxides in the elemental mass series Ti through Zn have been determined in three ionic liquids based on
choline chloride. The hydrogen bond donors used were urea, malonic acid, and ethylene glycol. The results obtained are compared with aqueous solutions
of HCl and NaCl."
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j_sum1
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VS. Thorough answer to what was a vague question.
Nice to have some specific detail on a DES and what it dissolves. I don't know the scale of the solvated units or whether they match the OP's concept
of a molecule. But these kinds of posts and referenced are gold.
Thanks.
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DraconicAcid
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| Quote: Originally posted by violet sin |
I losely use DES /IC interchangeably below, DEEP eutectic solvent and ionic liquid, referring to a non-standard solvent. Also not citing specific
examples so I hope it's not to incorrect .
____________
It doesn't dissolve them as Fe +++ and O - -, but it doesn't necessarily dissolve them as the empiracle formula either.
the metal oxides would be dissolved in a manner similar to soap and grime, no? Correct me if I'm wrong, personally I saw it as an encapsulation by
units of a charged or electronic nature, affecting things like lone pairs and disrupting bonds that are normally favored. promoting solovation by
making the aggregate unit cluster( metal oxide/ionic liquid/DES sheath) more favored than a solid complex of oxide. More of a masking the electronic
nature of the units from one another and moderating the difference between dissolved substance and neat solvent. |
If you dissolve a metal oxide in an ionic liquid, the ions of the liquid are surely going to react with those of the metal oxide. Chlorides from the
choline chloride will coordinate to the metal ions. The oxide ion is a very strong base, and will deprotonate other components of the melt. If you
dissolve Fe2O3 in choline chloride/malonic acid, you will get iron ions coordinated by chlorides, hydroxides, and malonates.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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DraconicAcid
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| Quote: Originally posted by veerenyadav | Thanks for putting wonderful perspectives.
(A) Does it mean that polymeric oxides ( Si, Ca, Na,... ) can be dissolved in a solvent ? |
Calcium and sodium oxides are simply ionic, and not polymeric. the only solvents that they may dissolve in without reacting are simple molten salts
such as alkali halides, hydroxides, or nitrates. Sodium oxide would surely deprotonate organic components of low-temperature melts containing choline
ion, urea, malonic acid, etc.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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chornedsnorkack
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Precisely how is, for example, NaOH dissolved in C2H5OH?
Ethanol is a weak acid. Therefore the reaction
NaOH+C2H5OH<->C2H5ONa+H2O
should be reversible. You could produce ethoxysodium, and then recover NaOH by reversing the reaction.
Does ethoxysodium dissolve in ethanol?
If yes, how?
Ethanol has dielectric permitivity lower than water. About 24, while water has 80.
Does ethoxysodium not dissolve in ethanol, or dissolve as ions, or dissolve as undissociated ethoxysodium molecules?
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DraconicAcid
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Sodium ethoxide will dissolve in ethanol as ions. Because of the low dielectric constant, the ions will be paired, but there will be no covalent bond
between the sodium and the ethoxide (and thus, not a molecule).
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chornedsnorkack
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Do micelles count as nanoparticles?
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veerenyadav
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Thanks to all
But if metal oxides remain as macromolecules in solid form then what happen these oxides get melted .
I mean still macrocrystal or single molecules ?
Or
What is blend of metal oxides melted togethor ?
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DraconicAcid
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| Quote: Originally posted by veerenyadav |
But if metal oxides remain as macromolecules in solid form then what happen these oxides get melted .
I mean still macrocrystal or single molecules ?
|
When a covalent network metal oxide gets melted, it breaks down into smaller macromolecules and large polyatomic ions.
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chornedsnorkack
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How polar are transition metal acetates?
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DraconicAcid
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They are generally ionic, so asking how polar they are is a non sequitur. How ionic they are will depend on the oxidation state of the metal.
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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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chornedsnorkack
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| Quote: Originally posted by DraconicAcid |
They are generally ionic, so asking how polar they are is a non sequitur. How ionic they are will depend on the oxidation state of the metal.
|
It is not non-sequitur.
Iron(III) forms a trinuclear complex, roughly Fe3O(CH3COO)7.
That turns out to be insoluble in water... but soluble in ethanol.
Being soluble in ethanol but not water hints at low polarity.
Also: although acetic acid is a stronger acid than ethanol, it is surprisingly low polarity. While the dielectric permittivity of ethanol is 24, that
of acetic acid is just 6,21.
The dielectric permittivity is quoted to be 27 at 80 % acetic acid by weight, 20 % water.
So, is concentrated acetic acid a good solvent for low polarity solutes? Such as molecular acetates?
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