How salty is a half salty solution? I mean, only one kind of ion

[Weissritter]

Well...I couldn't fit my question properly in the title. Feel free to propose a way of asking it
Please note, concentration will be ommited in order to make this topic easier.
Now, as tongue-d humans we are, we can feel the saltiness of a salt solution. Not a big deal up to here. The salt dissociates into it anion and cation. We have this in the most common salt solution, in water: Na⁺ and Cl^-.
But, what happens when you have only Na⁺ without Cl^-? Is it salty, half salty or is it somewhere in between? And in a Cl^- only solution?
Isolating ions is supposed to be possible, though I've never seen it.
You haven't seen PF's server, but keep in mind you rely on it.

 

[chill_factor]

you can isolate a SINGLE ion. Or maybe a group of say... 10. That'll require laser cooling and extremely precise measurements.

But in a solution there's something like 10^20-10^23. Even the most dilute solutions measurable have concentrations of 10^10 ions per liter. You simply can't do it.

 

[Weissritter]

you can isolate a SINGLE ion. Or maybe a group of say... 10. That'll require laser cooling and extremely precise measurements.

But in a solution there's something like 10^20-10^23. Even the most dilute solutions measurable have concentrations of 10^10 ions per liter. You simply can't do it.

The reason I said that was sort-of-using what a teacher said when explaining low-solubility salts. It was something like "If you mix two solutions, one with sulfide ions and other with Fe⁺³, they become one in the salt and precipitate quickly". So I thought it was possible.
Or...was it a way of explaining how those salts work, without considering actual experimental difficulties??

 

[jim mcnamara]

NaOH dissociates into Na and OH ions and is a strong base. HCl dissociates into H and Cl ions and is a strong acid. Either of these in moderate concentration may severely damage your mouth, tongue, esophagus when consumed.

NaCl dissociates into Na and Cl ions. So it is neither a strong acid nor a strong base.
Salt in moderate contration is a food stuff - pickle juice. Not that I am pushing pickle juice as a food, but it used to make, well, pickles, and when you consume pickles you get some dissolved NaCl. In a moderate concentration.

Reiswitter - does that show you why the way you asked your question does not make sense to us? I don't get what you want to know.

 

[Weissritter]

NaOH dissociates into Na and OH ions and is a strong base. HCl dissociates into H and Cl ions and is a strong acid. Either of these in moderate concentration may severely damage your mouth, tongue, esophagus when consumed.

NaCl dissociates into Na and Cl ions. So it is neither a strong acid nor a strong base.
Salt in moderate contration is a food stuff - pickle juice. Not that I am pushing pickle juice as a food, but it used to make, well, pickles, and when you consume pickles you get some dissolved NaCl. In a moderate concentration.

No problem up to here. I'm assuming that a human-noticeable quantity of Na⁺ can be isolated, because, I heard it happening with sulfide. With those ions a solution could be made, and it could or not feel salty, because it lacks the Cl^- ions in a normal salt solution.

Reiswitter - does that show you why the way you asked your question does not make sense to us? I don't get what you want to know.

My username wreacks havoc again
Rephrased, my question becomes: "Would a Na⁺ ONLY water solution FEEL as salty as a NaCl one?"

 

[Darwin123]

Well...I couldn't fit my question properly in the title. Feel free to propose a way of asking it
Please note, concentration will be ommited in order to make this topic easier.
Now, as tongue-d humans we are, we can feel the saltiness of a salt solution. Not a big deal up to here. The salt dissociates into it anion and cation. We have this in the most common salt solution, in water: Na⁺ and Cl^-.
But, what happens when you have only Na⁺ without Cl^-? Is it salty, half salty or is it somewhere in between? And in a Cl^- only solution?
Isolating ions is supposed to be possible, though I've never seen it.
You haven't seen PF's server, but keep in mind you rely on it.

I would call it a very high voltage solution!
Maybe even an electroheavy solution!

Sodium ions are positive. If you add sodium ions without negative ions to water, then the
solution will have a very large positive charge.

The large positive charge will produce a high positive voltage relative to the voltage at infinite distance. The precise value would depend on the capacitance of the solution, which may depend on the geometry. I leave it as an exercise in electromagnetic theory as to what the capacitance of this solution would be.

Also note that like charges repel. So the sodium ions will repel each other. You may have sodium ions jumping out of the water, accelerating outward.

The positive charge could be passed to water molecules, so you may have protons and hydroxyl ions jumping out of the water.

On the other hand, unlike charges attract. So you would have electrons accelerating toward the solution. Electrons would accelerate and hit the surface of the solution at high speed. There was a song a few decades back called "White Lightning". I think it would taste like that!

 

[Ygggdrasil]

The taste of NaCl is primarily due to taste cells that sense the presence of sodium ions through their sodium channels. Therefore, salts containing chloride but lacking sodium, such as RbCl or CsCl will not taste salty. Conversely, salts containing sodium but lacking chloride, such as NaNO2 or Na2SO4 will taste salty.

https://en.wikipedia.org/wiki/Taste#Saltiness

 

[SteamKing]

How does something 'feel' salty?

 

[Integral]

How does something 'feel' salty?

Guess you have never swam in the ocean.

Na when introduced to water reacts violently. During a boot camp demonstration a instructor dropped a fist sized chuck of Na into a 55gal drum of water. It immediately launched straight up about 50'.

 

[Borek]

The reason I said that was sort-of-using what a teacher said when explaining low-solubility salts. It was something like "If you mix two solutions, one with sulfide ions and other with Fe⁺³, they become one in the salt and precipitate quickly". So I thought it was possible.

Where does it say "separation of ions"?

 

[DrDu]

The taste of NaCl is primarily due to taste cells that sense the presence of sodium ions through their sodium channels. Therefore, salts containing chloride but lacking sodium, such as RbCl or CsCl will not taste salty. Conversely, salts containing sodium but lacking chloride, such as NaNO2 or Na2SO4 will taste salty.

https://en.wikipedia.org/wiki/Taste#Saltiness

I once tasted both RbCl and CsCl and they both taste kind of salty although not exactly like rocksalt. You can buy salt substitute which contains KCl. So situation is not that easy.

 

[Studiot]

Weissritter, your proposal for a solution containing only a single species of ion fails at the first hurdle since there must also be solvent ions present in an ionic solution, even if it were possible to support a single species in such a solution.

Isolating ions is possible, but surely, by the definition of isolation they are not in solution?

Ions exist in plasmas, and can be separated by electric and or magnetic fields, but these are not in solution and most definitely not for tasting.

If you are interested in an introductory treatment of the chemistry of taste look in the book

Molecules by Atkins

https://www.amazon.com/dp/0521535360/?tag=pfamazon01-20

 

[Weissritter]

The taste of NaCl is primarily due to taste cells that sense the presence of sodium ions through their sodium channels. Therefore, salts containing chloride but lacking sodium, such as RbCl or CsCl will not taste salty. Conversely, salts containing sodium but lacking chloride, such as NaNO2 or Na2SO4 will taste salty.

https://en.wikipedia.org/wiki/Taste#Saltiness

This was the answer I was looking for. In my defense, I can say my native-language wiki doesn't cover which salts are the 'salty' feeling ones. I'll add it soon.

I once tasted both RbCl and CsCl and they both taste kind of salty although not exactly like rocksalt. You can buy salt substitute which contains KCl. So situation is not that easy.

Sounds like the tongue detects them as if they were sodium, as they react the same way, but their way bigger atomic radius prevents many atoms to be detected at the same time, maybe?

I would call it a very high voltage solution!
Maybe even an electroheavy solution!

Sodium ions are positive. If you add sodium ions without negative ions to water, then the
solution will have a very large positive charge.

The large positive charge will produce a high positive voltage relative to the voltage at infinite distance. The precise value would depend on the capacitance of the solution, which may depend on the geometry. I leave it as an exercise in electromagnetic theory as to what the capacitance of this solution would be.

Also note that like charges repel. So the sodium ions will repel each other. You may have sodium ions jumping out of the water, accelerating outward.

The positive charge could be passed to water molecules, so you may have protons and hydroxyl ions jumping out of the water.

On the other hand, unlike charges attract. So you would have electrons accelerating toward the solution. Electrons would accelerate and hit the surface of the solution at high speed.


There was a song a few decades back called "White Lightning". I think it would taste like that!

I didn't ask for this but neither saw it coming. You remembered me the obvious I forgot to see, and you deserve a thank you. Seriously. You could feel your tongue electrons being pulled towards the solution

How does something 'feel' salty?

Taste salty, I mean taste salty.

Guess you have never swam in the ocean.

Na when introduced to water reacts violently. During a boot camp demonstration a instructor dropped a fist sized chuck of Na into a 55gal drum of water. It immediately launched straight up about 50'.

I was a child once, I was weak to bigger-than-me waves once, I don't remember how, but I ended up doing a somersault by the effects of the wave force in me and swallowing a lot of water. It was horrible. But you'll find something else than Na and K in water, I guess, like Li or d-group metals, right?
By adding metallic sodium to water you get NaOH, and a lot of energy. So the way here would start with a common salt with non-explosive sodium.

Where does it say "separation of ions"?

It doesn't say, I only thought it could be done since I deducted it from that statement. A while ago I thought it was possible.
Anyway, Ygggdrasil's answer fills the doubt.

Weissritter, your proposal for a solution containing only a single species of ion fails at the first hurdle since there must also be solvent ions present in an ionic solution, even if it were possible to support a single species in such a solution.

Isolating ions is possible, but surely, by the definition of isolation they are not in solution?

Ions exist in plasmas, and can be separated by electric and or magnetic fields, but these are not in solution and most definitely not for tasting.

If you are interested in an introductory treatment of the chemistry of taste look in the book

Molecules by Atkins

https://www.amazon.com/dp/0521535360/?tag=pfamazon01-20

Yeah...I didn't explain properly. I meant to take all the chloride (well, not all, but the most) in a NaCl solution, ending up in "only Na⁺ solution", which could or not feel salty, but Ygggdrasil ended up explaining.

 

[Studiot]

Yeah...I didn't explain properly. I meant to take all the chloride (well, not all, but the most) in a NaCl solution, ending up in "only Na+ solution", which could or not feel salty, but Ygggdrasil ended up explaining.

Several have told you that you cannot have a solution containing only one type of ion.
Yet you still persist in posting as though this is possible.

This is very confusing.

As an addition to the information supplied by Ygggdrasil you might like to note that pure sodium chloride tastes less 'salty' than impure.

This is one reason why some prefer to buy 'iodised salt' or sea salt for cooking. Potassium iodate offers neither chloride nor sodium ions.

 

[Ygggdrasil]

I once tasted both RbCl and CsCl and they both taste kind of salty although not exactly like rocksalt. You can buy salt substitute which contains KCl. So situation is not that easy.

Sounds like the tongue detects them as if they were sodium, as they react the same way, but their way bigger atomic radius prevents many atoms to be detected at the same time, maybe?

Yes, as the wikipedia article says, the sodium channels can detect other similar cations, just less efficiently. For example, it states that KCl tastes about half as salty as NaCl. So I agree with DrDu that, as with most things in biology, things are not so simple. But the point remains that salty taste is due to the sodium part of NaCl and not the chloride part.

As an addition to the information supplied by Ygggdrasil you might like to note that pure sodium chloride tastes less 'salty' than impure.

This is one reason why some prefer to buy 'iodised salt' or sea salt for cooking. Potassium iodate offers neither chloride nor sodium ions.

I think the main reason why people buy iodized salt is not for the taste, but because iodine is an essential nutrient and iodized salt can help prevent iodine deficiency.


With regard to taste vs feel, these two senses are not so different in some cases. Foods that taste spicy often contain the molecule capsaicin. Capsaicin activates a channel called TRPV1, which is normally activated by hot temperatures. Similarly, mint flavor contain molecules that activate cold-sensing channels like TRPM8. Other spicy foods (such as Sichuan peppers) can contain molecules that activate other pain receptors as well.

 

[Darwin123]

I didn't ask for this but neither saw it coming. You remembered me the obvious I forgot to see, and you deserve a thank you. Seriously. You could feel your tongue electrons being pulled towards the solution

The song was actually on a related topic. It described the behavioral and physiological effects of a dilute solution of water in ethanol, nicknamed "White Lightning". "White Lightning" is also called "Hill Billy Heroin" and "Clear-All".

The picturesque effects presented in the song almost as interesting as my conjecture of what an aqueous Na+ solution would be like. The difference is that "White Lightening" is a REAL drink.

 

[Weissritter]

Several have told you that you cannot have a solution containing only one type of ion.
Yet you still persist in posting as though this is possible.

This is very confusing.

As an addition to the information supplied by Ygggdrasil you might like to note that pure sodium chloride tastes less 'salty' than impure.

I'll ask my teacher directly as soon as I see him again. Thanks for siding with truth.

Yes, as the wikipedia article says, the sodium channels can detect other similar cations, just less efficiently. For example, it states that KCl tastes about half as salty as NaCl. So I agree with DrDu that, as with most things in biology, things are not so simple. But the point remains that salty taste is due to the sodium part of NaCl and not the chloride part.



I think the main reason why people buy iodized salt is not for the taste, but because iodine is an essential nutrient and iodized salt can help prevent iodine deficiency.


With regard to taste vs feel, these two senses are not so different in some cases. Foods that taste spicy often contain the molecule capsaicin. Capsaicin activates a channel called TRPV1, which is normally activated by hot temperatures. Similarly, mint flavor contain molecules that activate cold-sensing channels like TRPM8. Other spicy foods (such as Sichuan peppers) can contain molecules that activate other pain receptors as well.

You've unraveled a mystery I had for some years. Thanks!

The song was actually on a related topic. It described the behavioral and physiological effects of a dilute solution of water in ethanol, nicknamed "White Lightning". "White Lightning" is also called "Hill Billy Heroin" and "Clear-All".

The picturesque effects presented in the song almost as interesting as my conjecture of what an aqueous Na+ solution would be like. The difference is that "White Lightening" is a REAL drink.

 

[Studiot]

I'll ask my teacher directly as soon as I see him again. Thanks for siding with truth.

Sodium ions are much smaller than chloride ions so
I could imagine a container, separated into two by a semi permeable membrane, such that only the sodium ions (edit and possibly solvent ions) could pass through.

Put pure water into one half and salt solution into the other.
The chloride ions would remain in one half of the container, but the pure water half would soon contain some sodium ions that had passed through so you would have some solution containing only one species of solute ion.

However as I already noted in post#12 there would also be other ions in the pure water half, due to some ionic dissociation of the solvent water.

Can you guess what else would happen to maintain electrical neutrality?

 

[Weissritter]

However as I already noted in post#12 there would also be other ions in the pure water half, due to some ionic dissociation of the solvent water.

Can you guess what else would happen to maintain electrical neutrality?

As said before, electrons would be attracted, and that's how much I can guess. Electron jumping from s sublevel to higher ones sounds too much to be possible, so the best I can guess is the electron-leeching effect.

 

[Borek]

Electrons would stick to their ions, so they would not change the charge distribution.

If anything I would expect to see changes in the concentrations of other ions in the solution.

Please remember that moving ions through the membrane as Studiot suggested means creating charge separation. Charge separation means potential difference - and any measurable change in concentrations would require pretty high voltages.

 

[Studiot]

Borek, ( or any practising chemist) you got there first and if you have better information please post it. Particularly about the practical availability of suitable molecular sieves/membranes.

Electrons are not ions, nor would they exist in a free state in solution.

I don't know if you are aware but ionic solvents work by splitting into ions (dissociation).
The solvent starts out electrically neutral so the resulting charges on tha anions (-ve) and cations (+ve) it splits into balance out, amintaining the electrical neutrality.

Two such solvents for sodium chloride are ammonia and water, the salt being about three times as soluble in water as ammonia.

When an (electrically neutral) salt dissolves in an ionic solvent it also splits up into ions.
In the same way electrical neutrality is maintained by balancing out the charges of the anions and cations created from the solvent molecules.

I have tried to show this in the attachment.

If we have our container with a watertight door over the membrane initially and fill each side up as shown in Fig 1 we will have only solvent ions in the left hand side and solvent ions plus solute ions in the right.

I have appended the approximate sizes of the ions so you can see that the sodium and chloride ions are much bigger than the sovent ions from the water.

So the solvent ions can pass freely through the membrane, as can the sodium ions. However the membrane is such that the chloride ions (about twice the size of the sodium) are too big to pass the membrane.

Thus in Fig2 when we open the door the sodium ions (but not the chloride ions) will spread (diffuse) into the left hand chamber.
Because cations (Na⁺) are spreading left, they will displace some solvent cations in the left hand chamber to the right hand one.
So you will end up with only sodium and solvent ions in the left hand chamber. You cannot avoid the solvent ions since the salt would not dissolve without them.

It is this movement of solvent ions that maintains overall electrical neutrality.

This is a very simplistic description of what happens that I'm sure will horrify the pure chemists but I hope it serves to promote understanding.

Whilst we are on the subject can you say why the cations are in general smaller than anions?

 

[Borek]

This is a very simplistic description of what happens that I'm sure will horrify the pure chemists but I hope it serves to promote understanding.

Can't say I disagree. The main problem is that what you wrote seems to be suggesting all ions get separated the way you wrote them, while in fact only some small amounts will move through the membrane. But on some general level you are right about processes taking place.

 

[Studiot]

while in fact only some small amounts will move through the membrane

You are right I meant to mention at the end that the diffusion would not proceed very far, but forgot.

 

[DrDu]

http://en.wikipedia.org/wiki/Gibbs–Donnan_effect

 

[Weissritter]

You guys are really helpful. I won't say that an only-one ion solution exists, and having you all clarified this, the diffusion chat may proceed.
It is sad to see the diffusion would create the sodium-and-hydronium-and-hydroxide to a very limited extent, but that's how it works. Thank you Studiot for your diagram. Thank you all.
Even though my doubts on this subjects have been currently clarified, I, with all my magnanimity will allow further posts with relevance to the thread

 

[Studiot]

It is sad to see the diffusion would create the sodium-and-hydronium-and-hydroxide to a very limited extent, but that's how it works.

Dissociation creates the ions.

Diffusion moves them about.

The hydroxyl (negative) and hydroxonium (english) or hydronium (american) (positive) are always present to some extent. The addition of other substances changes the amount present.

I noted in my first post that the conditions under which you could isolate a single ionic species are not the sort of conditions where you would go taste sampling them.

 

[Weissritter]

I noted in my first post that the conditions under which you could isolate a single ionic species are not the sort of conditions where you would go taste sampling them.

Yes, both of us have issues about having plasma in the mouth. We'd need a volunteer to know what it could taste like for a human. If micromass hears about this, I think I know who he'd nominate.