Hey there my expert friends! My question today is discussing the formation of matallics! I had a chat with the youtuber OwlTech who was very helpful about the subject, and he had said that precipitation had to do with negative charged compounds which take the added electron from the aqueous "metal" solution which has a positive charge. My question would be if this is the case SMB has a valency charge of (-2) with the bisulfite being the main reactant, so would sodium bicarbonate work as well being also a (-2) valency charged compound? I actually saw OwlTech use it after I went on the research escapade, but he has also used sodium hydroxide, and fomic acid, but I am unsure why. He has said this: "it's the CO that does the trick from decomposition of fomic acid", but carbon monoxide (CO) has a zero ionic charge. My main question would be can sodium carbonate replace SMB for precipitation, or even be able to deNOx a solution replacing urea, and other compounds? Also, what else is at play for precipitation other than ionic charge relationships? Thanks everyone for your answers to my other questions so far, and for this thread as well! A very helpful, polite, and informative community.
Precipitating Metallics.
- Thread starter CattMurry
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S of bisulphite or SO2 is +4, going to +6 on reduction (or precipitation) hence action is -2. Required also correct potential between reductant and oxidizer.
CO2 does not have that ability.
Formic acid can also turn to CO2, thus giving 2 electrons
CO2 does not have that ability.
Formic acid can also turn to CO2, thus giving 2 electrons
If I understand correctly you have said that the SO2, and SMB have the ionic action of (-2) due to them giving the 2 electrons? but the formic acid/CO2 does not have that action? Just a little confused on the last part there of: "thus giving 2 electrons". Wouldn't the formic/CO2 have the same tradeoff, or ionic action? Thanks for the answer. Just wanted to also ask about the Sodium Carbonate's action as well, and thanks for the patience if I have this backwards haha.
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We can give electrons back to an ionic compound to change its valence or even reduce the ionic salt back to being an elemental metal, or even change the type of ionic salt the metal ions is (say from being a metal chloride salt into becoming a metal sulfate salt where one metal may precipitate from solution and a different metal may not become insoluble), by the use of many different chemicals or metals.
Not all metal ions react the same to a change in valence or a to a change in the type of salt it is, or to the ionic salt that it can form, some metals may precipitate and others may not in an adjustment of their valence, or its type of ionic compound from the same solution.
We normally make adjustments with certain chemicals or metals or use certain reducing agents to selectively remove or change certain metal ions from solution while leaving others in solution, like removing lead from solution while leaving the gold in soluble form, even if both metal ions valence has been changed or they both can change the types of salts they are or could become.
But our goal may not be to just change the valence of the solution, with just any chemical or metal that we can use. We may have several different metal ions in solution at once, and we do not wish to change them all at once or reduce them or precipitate large groups of different metals at once.
Our goal may not be to reduce all metals in solution back to elemental form, or to precipitate most anything, or just anything from the solution, or to convert large groups of different metal ions to a carbonate, hydroxide, or oxide or to some other elemental form.
We are picky refiners, and also tend to be selective in what metal or metals we wish to convert or change in form or valence.
We want to separate the different metals from solution selectively and cleanly as possible as much as we can we try to which metals we reduce from solution and which ones we don't, which chemical or metal that will be more selective for the ions we are after, or where one metal may precipitate by changing the valence...
Not all metal ions react the same to a change in valence or a to a change in the type of salt it is, or to the ionic salt that it can form, some metals may precipitate and others may not in an adjustment of their valence, or its type of ionic compound from the same solution.
We normally make adjustments with certain chemicals or metals or use certain reducing agents to selectively remove or change certain metal ions from solution while leaving others in solution, like removing lead from solution while leaving the gold in soluble form, even if both metal ions valence has been changed or they both can change the types of salts they are or could become.
But our goal may not be to just change the valence of the solution, with just any chemical or metal that we can use. We may have several different metal ions in solution at once, and we do not wish to change them all at once or reduce them or precipitate large groups of different metals at once.
Our goal may not be to reduce all metals in solution back to elemental form, or to precipitate most anything, or just anything from the solution, or to convert large groups of different metal ions to a carbonate, hydroxide, or oxide or to some other elemental form.
We are picky refiners, and also tend to be selective in what metal or metals we wish to convert or change in form or valence.
We want to separate the different metals from solution selectively and cleanly as possible as much as we can we try to which metals we reduce from solution and which ones we don't, which chemical or metal that will be more selective for the ions we are after, or where one metal may precipitate by changing the valence...
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Okay, so him stating that the monoxide (CO) doing something is irrelevant then? While CO2/Formic does have the same reaction, but it is not the appropriate action required? What do you mean by the sodium oxide, and carbonate not having the same action? Is that in relation to each other, or comparing their reaction to the stated reactions above? The youtuber just explained it as a ionic action of (-2) which cements matallics due to them getting their electrons back. In such case I would then assume any compound like baking soda (sodium carbonate) which does have that ionic action of (-2) to be sufficient from what was said. I was curious if there was anything else to it than just that, or if it truly just requires that (-2) action. Thanks for the replies!
Not quite sure what this explains, but thanks for the reply nonetheless! I am aware of pickiness, and the process of creating salts, or other changes to maneuver around the aqueous compounds to then drop, or react what you want. Such example that is clear is how some people choose to put everything (precious metals) into solution, then use the ionic action of HCL (-1) ionic charge to bump, or precipitate silver chloride (0) ionic charge from it's silver nitrate aqueous (-1) ionic charge if I'm not mistaken. After that you give another electron to the chloride salts to make Silver Oxide with a ionic charge back to (+1) with hydroxide, or other compounds.
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You're confusing two different principles.
When we precipitate gold from a solution, we usually do so by "reducing" it. Gold has been oxidized to put it into solution. As it is oxidized it gives up electrons and it changes from a solid metal to an ion in solution. A reducing agent, like SMB or ferrous sulfate, gives up electrons to the gold, which then changes from an ion back to a solid metal.
When we precipitate silver from a solution, we can either reduce it or we can create a nearly insoluble compound that precipitates. If we use copper to cement the silver from solution we are reducing it. The solid, metallic copper gives up electrons to the ionic silver that is in solution. The silver is reduced and precipitates as a solid metal as the copper is oxidized and becomes an ion in the solution, replacing the silver. But if we add HCl or table salt (NaCl), the chloride ions combine with the silver ions to form silver chloride (AgCl), which is nearly insoluble and the AgCl precipitates.
In all these cases, we have a precipitate that collects on the bottom of our beakers. But in some cases the precipitate is a solid metal while in others it is a compound of our target metal combined with another element or ion.
Dave
When we precipitate gold from a solution, we usually do so by "reducing" it. Gold has been oxidized to put it into solution. As it is oxidized it gives up electrons and it changes from a solid metal to an ion in solution. A reducing agent, like SMB or ferrous sulfate, gives up electrons to the gold, which then changes from an ion back to a solid metal.
When we precipitate silver from a solution, we can either reduce it or we can create a nearly insoluble compound that precipitates. If we use copper to cement the silver from solution we are reducing it. The solid, metallic copper gives up electrons to the ionic silver that is in solution. The silver is reduced and precipitates as a solid metal as the copper is oxidized and becomes an ion in the solution, replacing the silver. But if we add HCl or table salt (NaCl), the chloride ions combine with the silver ions to form silver chloride (AgCl), which is nearly insoluble and the AgCl precipitates.
In all these cases, we have a precipitate that collects on the bottom of our beakers. But in some cases the precipitate is a solid metal while in others it is a compound of our target metal combined with another element or ion.
Dave
Good explanation Dave. Side reactions, or many different intermediates can make it hard to keep track of haha. Looks like silver chloride does have some decent solubility in ammonia, and even apparently hitting it with light will bring it back to the oxide. Fascinating stuff. Still a little confused on why baking soda isn't just thrown at everything if it does give electrons as well. For the rest of understanding how some metals dissolve, and precipitate over other metals first the reactivity metals chart says it all, but of course it is not so clear cut in many situations, and practice. (if any of this is inaccurate do correct! I am no chemist haha.)
Still a little confused on why baking soda isn't just thrown at everything if it does give electrons as well.
We are not trying to convert everything carbonates or oxides.
The reactivity series does not explain it all, although it is a very helpful tool like our others to give some explanation.
some metal ions will precipitate with an alkaline substance (like ammonia or hydroxide...) and then redissolve in excess of that same alkaline solution... Look into the amphoteric metals, although gold is one of those metals, although the gold ions would have to be subjected to more extreme conditions than many of the more reactive metals.
it is about electrons, either lose or gain of, or of sharing or trading places in ionic solutions,
There are many factors that can come into play, Not just valence. and many different conditions that can affect results on the chemistry of the metals or their ionic compounds. valence is not all there is to it.
We are not trying to convert everything carbonates or oxides.
The reactivity series does not explain it all, although it is a very helpful tool like our others to give some explanation.
some metal ions will precipitate with an alkaline substance (like ammonia or hydroxide...) and then redissolve in excess of that same alkaline solution... Look into the amphoteric metals, although gold is one of those metals, although the gold ions would have to be subjected to more extreme conditions than many of the more reactive metals.
it is about electrons, either lose or gain of, or of sharing or trading places in ionic solutions,
There are many factors that can come into play, Not just valence. and many different conditions that can affect results on the chemistry of the metals or their ionic compounds. valence is not all there is to it.
I don´t think we can judge this so easily, but i could give my bit of experience with theory here.
The assumption with "negatively charged" particles... I thing i get somehow what it should mean: metal ion in solution is positively charged (cation). in order to get it back to the metal, it must come to the contact with some "negatively charged" particle, which give the electrons to it, make it precipitate as non-charged metal.
I will not consider it this way, but in very simple (and clearly somewhat misleading) way, OK. Could be used to disclose chemistry in "friendly way" for non-chemists
Thing is, as it was stated by more of us here, compound which cause metal cation to go back to the non-charged metallic form need not to be charged. It just need to have some electrons to offer
Here we come to thing called "redox potential". I think the best approach to disclose what is happening in your pot.
All particles/chemicals in your solution want to get in the form, where they would have the lowest energy possible. There are chemicals that very kindly pass electrons, and there are chemicals that very kindly accept some. Ones are in our eyes "reducing agents" and the others "oxidating agents". Oxidants accept electrons, reducers pass electrons.
This is when the "redox potential" comes into the game. Redox describes certain half-reactions in volts, compared to so called "standard hydrogen electrode". Not exactly needed to explain what it precisely is, but it is our "zero potential".
As we mix together two chemicals, say gold chloride and sodium sulfite, they will interact together.
We could describe this in two half-reactions:
-reduction of Au3+ to metallic gold: Au3+ + 3 electrons ---> Au(0)
-oxidation of sulfite to sulfate anion: SO3- + H2O - 2 electrons --->HSO4- + H+
We focus only on the electron transfer reactions. Everything else is ommited for clarity. Sodium and chloride ions combine to make NaCl, but really they dont gain or loose electrons, so they dont figure in half reactions.
Both have they redox potential. Half-reaction with gold has value of +1,40 V. Half reaction for sulfur dioxide has value of +0,40 V (these values differ as temperature, concentration and other ions are taken in consideration).
When combined to give result: oxidant minus reductant. +1,40 - 0,40 = +1,0 V
Value is positive. This indicates, that reaction will proceed.
If we take copper for example:
Cu2+ + 2 electrons ---> Cu(0), this half-reaction has potential of +0,34 V.
If we try to combine this copper half reaction with above sulfite reaction, we will find that +0,34 - 0,4 = -0,06 V
Value is negative, so reaction will not proceed.
This is theory. In real world, ions are complexed with other ligands (AuCl3 in solution likely form AuCl4- = lowering the energy), temperature, concentration and other factors hassle with these ideal conditions numbers.
But this is what is happening. It could be considered as some kind of trade.
When somebody try to sell you some stuff, you could accept or reject the offer. The same happens with chemicals in your pot. Copper in solution rejects the sulfite offer, but gold kindly accept it
Thank you all for the knowledge silo. Very informative and helpful.
Nice in depth explanation my friend. This was the part I had a hard time finding where to even start looking:I don´t think we can judge this so easily, but i could give my bit of experience with theory here.
The assumption with "negatively charged" particles... I thing i get somehow what it should mean: metal ion in solution is positively charged (cation). in order to get it back to the metal, it must come to the contact with some "negatively charged" particle, which give the electrons to it, make it precipitate as non-charged metal.
I will not consider it this way, but in very simple (and clearly somewhat misleading) way, OK. Could be used to disclose chemistry in "friendly way" for non-chemists
Thing is, as it was stated by more of us here, compound which cause metal cation to go back to the non-charged metallic form need not to be charged. It just need to have some electrons to offer
Here we come to thing called "redox potential". I think the best approach to disclose what is happening in your pot.
All particles/chemicals in your solution want to get in the form, where they would have the lowest energy possible. There are chemicals that very kindly pass electrons, and there are chemicals that very kindly accept some. Ones are in our eyes "reducing agents" and the others "oxidating agents". Oxidants accept electrons, reducers pass electrons.
This is when the "redox potential" comes into the game. Redox describes certain half-reactions in volts, compared to so called "standard hydrogen electrode". Not exactly needed to explain what it precisely is, but it is our "zero potential".
As we mix together two chemicals, say gold chloride and sodium sulfite, they will interact together.
We could describe this in two half-reactions:
-reduction of Au3+ to metallic gold: Au3+ + 3 electrons ---> Au(0)
-oxidation of sulfite to sulfate anion: SO3- + H2O - 2 electrons --->HSO4- + H+
We focus only on the electron transfer reactions. Everything else is ommited for clarity. Sodium and chloride ions combine to make NaCl, but really they dont gain or loose electrons, so they dont figure in half reactions.
Both have they redox potential. Half-reaction with gold has value of +1,40 V. Half reaction for sulfur dioxide has value of +0,40 V (these values differ as temperature, concentration and other ions are taken in consideration).
When combined to give result: oxidant minus reductant. +1,40 - 0,40 = +1,0 V
Value is positive. This indicates, that reaction will proceed.
If we take copper for example:
Cu2+ + 2 electrons ---> Cu(0), this half-reaction has potential of +0,34 V.
If we try to combine this copper half reaction with above sulfite reaction, we will find that +0,34 - 0,4 = -0,06 V
Value is negative, so reaction will not proceed.
This is theory. In real world, ions are complexed with other ligands (AuCl3 in solution likely form AuCl4- = lowering the energy), temperature, concentration and other factors hassle with these ideal conditions numbers.
But this is what is happening. It could be considered as some kind of trade.
When somebody try to sell you some stuff, you could accept or reject the offer. The same happens with chemicals in your pot. Copper in solution rejects the sulfite offer, but gold kindly accept it
-"Thing is, as it was stated by more of us here, compound which cause metal cation to go back to the non-charged metallic form need not to be charged. It just need to have some electrons to offer.
Here we come to thing called "redox potential". I think the best approach to disclose what is happening in your pot."
Then:
-"This is when the "redox potential" comes into the game. Redox describes certain half-reactions in volts, compared to so called "standard hydrogen electrode". Not exactly needed to explain what it precisely is, but it is our "zero potential".
This is why I came here. I couldn't understand how it could be that easy as in (just finding - charged compounds). It all has a lot of arms to it due to the redox potential, valency, How much of what is in "the pot", temperatures, environment, or atmosphere, and I'm sure a bit more. Apologies to the other users for not having those facts stick to my understanding due to my ignorance! I need basically all the details at once to even start understanding this complex web. This will help clarify, but do you know where I can learn a bit more on that half reaction math? Those are some basic, but wonderfully put examples for my potato head lmao. Thanks again for this!
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I understand... I think. For your example there is a balance, or goldie locks zone for many things, and when the acid, or alkaline reactants get too concentrated it then becomes resoluble into the solution, and even vise versa. I did not mean to say the metals reactivity chart is the golden tool of knowledge for this either haha.
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We use many different tools to try and describe what could happen or try and describe what is happening, or to get some kind of guess why something is not happening that we expected to, valence change, is only one of the tools.
Things like temperatures boiling points, acidity or pH, concentration as well as other factors also come into these figures of how reactions may proceed,
Exchange of metal ions, electron movement, potential difference, and general chemistry, valence is only one tool we have many more tools in the toolbox,.
Solubility, KSP and or the solubility rules, ORP, oxidation or reduction potentials, redox reactions, chemical and physical reactions, oxidants and reducing agents, selectivity, catalytic actions, anion and cation exchange, rationalizations, precipitations, crystallizations writing and balancing chemical reactions or equations, vaporizations, charge or dissociation of electrically charged ions, ionic exchange, specific gravity, electron shells of different metals and the movement of electrons, molar concentration, percent hydrogen, atomic weights, and chemical conversion...
Things like temperatures boiling points, acidity or pH, concentration as well as other factors also come into these figures of how reactions may proceed,
Exchange of metal ions, electron movement, potential difference, and general chemistry, valence is only one tool we have many more tools in the toolbox,.
Solubility, KSP and or the solubility rules, ORP, oxidation or reduction potentials, redox reactions, chemical and physical reactions, oxidants and reducing agents, selectivity, catalytic actions, anion and cation exchange, rationalizations, precipitations, crystallizations writing and balancing chemical reactions or equations, vaporizations, charge or dissociation of electrically charged ions, ionic exchange, specific gravity, electron shells of different metals and the movement of electrons, molar concentration, percent hydrogen, atomic weights, and chemical conversion...
I'm aware of this, but thank you for the full scope of vocabulary, and reiteration.
Well, i am having trouble explaining and you apparently do not understand what I am trying to say.
What are you having issue explaining? I simply only wondered if the youtuber was being honest which he was, but his explanation is quite a bit simplified. None of you really answer strait forward the main question either. Baking soda is a reducer, and it neutralizes many acids that I can think of just like SMB, and others. Obviously you wouldn't just throw it into a melting pot of solutions lol. You would for example make peracetic acid solution to put all reactive metals like lead, tin, zinc, and so on into solution. Maybe a H2O, then HCL washing to make sure there's no random crud around (of course Cu will resist this step if present). Then knowing what else you have in here (lets assume silver, gold,) it would be nitric to eat the silver into its nitrate. Decant, or filter. Precipitate Silver aqueous with HCL, or salt, then in your other container (Au pot) you could go AP route, Chlorine route, or aqua Regia route. Then precipitate the Au with SMB after PH is controlled (in all these instances of precipitation this would be the case for controlling PH). I was simply asking why can't Sodium carbonate reduce it out if it is a reducer. I got every obvious answer but my question really. Lol. So what is hard to explain, and what exactly am I not understanding in all of this? Of course I do not know libraries of knowledge on every reaction, but I realize you wouldn't reduce everything at once, and PH of solution matters along with temperature, and all those other things.
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Basically what I am looking for is the knowledge that points to the action, or paper describing why hydroxides are preferred, or things like SMB, salt, even HCL, and many other's for dropping metals from solutions. I have seen combinations with baking soda, but not just itself used. Was just curious on Sodium carbonates reactions, uses, it's downfalls, and it's potential, or non-potential, and why basically. In my head yes to dissolve things there are many routs to take, but to get the actual oxides, or metallics.... they just end up as metallics. Meaning it seems very strait forward if you have of course the right conditions in your solution. Just wondering on that, because the dropping action seems like there are many different ways to just form the metals back to their metallic state, but it always ends with their matallic state. Rather than the metals going into solution which takes many forms. So, again. I am curious on reducers, and what action they are all doing to do the same thing, and why some are used at the price they are.
*I should add that some reducing agents are bases, and some are acids for obvious reasons. Such example is chlorine rout. Obviously you aren't looking to eat your beaker and adding more caustic/alkaline substances which will for the most part not help in any way. Maybe they can due to what was explained by making a solution too basic/acidic, but that's what I am asking about as well. Where is this math, papers, or diagram for this "goldie locks" zone as I had put it.
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I also found what you were saying when it was in my face the entire time. SMB is an example of what you were referring to:I don´t think we can judge this so easily, but i could give my bit of experience with theory here.
The assumption with "negatively charged" particles... I thing i get somehow what it should mean: metal ion in solution is positively charged (cation). in order to get it back to the metal, it must come to the contact with some "negatively charged" particle, which give the electrons to it, make it precipitate as non-charged metal.
I will not consider it this way, but in very simple (and clearly somewhat misleading) way, OK. Could be used to disclose chemistry in "friendly way" for non-chemists
Thing is, as it was stated by more of us here, compound which cause metal cation to go back to the non-charged metallic form need not to be charged. It just need to have some electrons to offer
Here we come to thing called "redox potential". I think the best approach to disclose what is happening in your pot.
All particles/chemicals in your solution want to get in the form, where they would have the lowest energy possible. There are chemicals that very kindly pass electrons, and there are chemicals that very kindly accept some. Ones are in our eyes "reducing agents" and the others "oxidating agents". Oxidants accept electrons, reducers pass electrons.
This is when the "redox potential" comes into the game. Redox describes certain half-reactions in volts, compared to so called "standard hydrogen electrode". Not exactly needed to explain what it precisely is, but it is our "zero potential".
As we mix together two chemicals, say gold chloride and sodium sulfite, they will interact together.
We could describe this in two half-reactions:
-reduction of Au3+ to metallic gold: Au3+ + 3 electrons ---> Au(0)
-oxidation of sulfite to sulfate anion: SO3- + H2O - 2 electrons --->HSO4- + H+
We focus only on the electron transfer reactions. Everything else is ommited for clarity. Sodium and chloride ions combine to make NaCl, but really they dont gain or loose electrons, so they dont figure in half reactions.
Both have they redox potential. Half-reaction with gold has value of +1,40 V. Half reaction for sulfur dioxide has value of +0,40 V (these values differ as temperature, concentration and other ions are taken in consideration).
When combined to give result: oxidant minus reductant. +1,40 - 0,40 = +1,0 V
Value is positive. This indicates, that reaction will proceed.
If we take copper for example:
Cu2+ + 2 electrons ---> Cu(0), this half-reaction has potential of +0,34 V.
If we try to combine this copper half reaction with above sulfite reaction, we will find that +0,34 - 0,4 = -0,06 V
Value is negative, so reaction will not proceed.
This is theory. In real world, ions are complexed with other ligands (AuCl3 in solution likely form AuCl4- = lowering the energy), temperature, concentration and other factors hassle with these ideal conditions numbers.
But this is what is happening. It could be considered as some kind of trade.
When somebody try to sell you some stuff, you could accept or reject the offer. The same happens with chemicals in your pot. Copper in solution rejects the sulfite offer, but gold kindly accept it
"Thing is, as it was stated by more of us here, compound which cause metal cation to go back to the non-charged metallic form need not to be charged."
I did not notice that SMB is at 0 charge itself, and that its reaction into SO2 is actually what is doing the "dropping/cementing/etc". I've seen SO2 bubbled into solutions, and it looked heavily ineffective, or just takes forever, so I didn't even think it would be the gas. "SO2 cements out the metals with sodium ions", is what one user on here (website) from another post had said, but how is this if it is only made of Sulfur, and oxygen? I just get to this: Sulfur dioxide can bind to metal ions as a ligand to form metal sulfur dioxide complexes, typically where the transition metal is in oxidation state 0 or +1. So, is it the sulfur itself, or as one user had said in another post Na binding ? Also, I still can't find for the life of me redox action potential of different compounds. Ah, standard reduction table. Found it. Of course at 25c, but how can I see different tables for heat?
Now my head hurts. lmao.
