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Eddygp
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Acetic Acid and Sodium Chloride
It turns out that mixing 8% acetic acid with common salt does generate a significant amount of hydrochloric acid: I moved a beaker containing an
ammonia solution to it and the ammonium chloride vapour/crystals formed rapidly!
Just surprised at this...
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Adas
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It was probably just ammonium acetate, HCl was not formed.
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Eddygp
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Does ammonium acetate form in the gas phase?
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Endimion17
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If you're implying that ammonium chloride smoke from the classical reaction is in gas phase, you're wrong. It's an aerosol. Solid particles = smoke.
I don't remember I saw such smoke with ammonia and acetic acid fumes. It might be because it's too hygroscopic... Just a guess.
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DraconicAcid
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Quote: Originally posted by Endimion17  |
If you're implying that ammonium chloride smoke from the classical reaction is in gas phase, you're wrong. It's an aerosol. Solid particles = smoke.
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It's not *in* the gas phase, but it *forms in* the gas phase (from gaseous reactants).
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Eddygp
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I meant what DraconicAcid said, that it forms from gaseous reactants. So I saw the classic white ammonium chloride forming in the air.
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SM2
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AA never gets quite dry. As far as forming aq HCL from weenigar and salz, to me it doesn't seem theoretically possible. But I'm not nearly as smart
as many are here, so consider it a guess. However; you can clean old pennies using a little vinegar and table salt. Is it the scrubbing action of the
salt along with acetic acid. Are we to assume on most old pennies, the dirty film consists of various amounts of whatever, including copper
carbonate, and then the acetic acid alone would work. More experiments to be done. Haven't taken a pH meter to it, but my nose did seem to smell HCL
from the mixture of salt and white vinegar, where the salt was in much greater proportion to the vinegar. just wet a small pile of table salt with
maybe 10 drops of white vinegar.
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Eddygp
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Yes, I decided to test it because of the smell. If it has formed, it won't be in large quantities, logically, but it has been enough for me to be able
to detect it with ammonia (NH3+HCl=NH4Cl), giving a positive result. Moreover, I had covered the glass with a metal tap (the one of a jam jar), and it
seems to have rusted at the edges... Very interesting.
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Adas
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| Quote: Originally posted by Eddygp | | Yes, I decided to test it because of the smell. If it has formed, it won't be in large quantities, logically, but it has been enough for me to be able
to detect it with ammonia (NH3+HCl=NH4Cl), giving a positive result. Moreover, I had covered the glass with a metal tap (the one of a jam jar), and it
seems to have rusted at the edges... Very interesting. |
Chloride ions may act as catalysts, e.g. when you clean pennies with vinegar + NaCl, and solutions of NaCl are capable of slowly dissolving Al foil.
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Eddygp
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I know, but what I'm trying to say is that some HCl formed, because the reaction I stated only occurs with gaseous HCl and NH3 from an adjacent
beaker, also in gas form.
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franklyn
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So that's why people are dropping dead in restaurants ,
it's the vinaigrette on their salads.
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bahamuth
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IIRC hydrochloric acid is formed in situ in some reactions by the action of acetic acid upon sodium chloride, though I do not remember where
or what.
I doubt that the hydrochloric acid formed reaches any appreciable amount, much less enough to escape the mix as gas and form ammonium chloride with
ammonia. My guess it that you have seen ammonium acetate forming, as this reaction is visually analogous to NH4Cl formation.
Only reference I bothered find for this is from the University of Minnesota.
http://www.chem.umn.edu/outreach/card-saltvincopper.html
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Eddygp
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It would probably be ammonium acetate, but I did notice a stench similar to that of hydrochloric acid, apart of the "vinegary" smell.
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AJKOER
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| Quote: Originally posted by bahamuth | IIRC hydrochloric acid is formed in situ in some reactions by the action of acetic acid upon sodium chloride, though I do not remember where
or what.
I doubt that the hydrochloric acid formed reaches any appreciable amount, much less enough to escape the mix as gas and form ammonium chloride with
ammonia. My guess it that you have seen ammonium acetate forming, as this reaction is visually analogous to NH4Cl formation.
Only reference I bothered find for this is from the University of Minnesota.
http://www.chem.umn.edu/outreach/card-saltvincopper.html |
Hydrometallurgy frequently employs weak acids (citric, tartaric,..) in highly ionic salt solutions to dissolve ores. This is simply a matter of
economics, and more recently, green economics (more environmentally friendly ore processing).
My understanding is that in water stressed conditions (from high concentrations of NaCl, MgCl2, FeCl3,..) the strength (or 'activity level') of even
otherwise weak acids (or very dilute strong acids) is significantly increased.
This may be at play here, hence the reference source (http://www.chem.umn.edu/outreach/card-saltvincopper.html ) comment, to quote:
"Explanation:
Salt, or sodium chloride, combines with acetic acid from the vinegar to produce sodium acetate and hydrogen chloride. Hydrogen chloride is a strong
acid and the combination of it and sodium acetate rapidly cleans the surface of the penny"
But the explanation is not correct, IMHO, as it is stilled the stronger acetic acid, not the HCl, accounting for the reaction on the surface of the
penny.
[Edited on 22-3-2013 by AJKOER]
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DraconicAcid
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| Quote: Originally posted by AJKOER | Hydrometallurgy frequently employs weak acids (citric, tartaric,..) in highly ionic salt solutions to dissolve ores. This is simply a matter of
economics, and more recently, green economics (more environmentally friendly ore processing).
My understanding is that in water stressed conditions (from high concentrations of NaCl, MgCl2, FeCl3,..) the strength (or 'activity level') of even
otherwise weak acids (or very dilute strong acids) is significantly increased. |
Citrate and tartrate will form complex ions with transition metals, rendering the metals more soluble, and increasing their acidity. Sodium chloride,
on the other hand, may have an effect simply by increasing the ionic strength of the solution.
| Quote: | This may be at play here, hence the reference source (http://www.chem.umn.edu/outreach/card-saltvincopper.html ) comment, to quote:
"Explanation:
Salt, or sodium chloride, combines with acetic acid from the vinegar to produce sodium acetate and hydrogen chloride. Hydrogen chloride is a strong
acid and the combination of it and sodium acetate rapidly cleans the surface of the penny"
But the explanation is not correct, IMHO, as it is stilled the stronger acetic acid, not the HCl, accounting for the reaction on the surface of the
penny. |
I think the only thing the salt does in the "penny-cleaning" reaction is to provide chloride ion to complex with the copper ions. I could be wrong.
[Edited on 22-3-2013 by DraconicAcid]
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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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AJKOER
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On re-thinking, my same argument (increased acid strength for a weak acid in a water stressed high ionic environment) means that adding a few drops of
hot vinegar to a pile of salt may be able to form a small amount of gaseous HCl (which may be tested with ammonia fumes). Alternately, one could argue
that the concentrated brine solution just makes the Acetic acid more volatile and easier to distill (an observation employed successfully in
concentrating acids).
However, IMHO no net HCl will be formed in a closed system as I suspect the reverse reaction occurs (HCl gas in contact with moist Sodium Acetate
forms NaCl and Acetic acid). In other words, the odor of HCl may be fleeting in a closed container.
One could assume, at best, a reaction parallel to the action of HOCl on NaCl:
NaCl + HOCl <--> NaOH + Cl2
where the smell of Cl2 is at first evident, but the equilibrium is re-established and the chlorine smell dissipates (see http://books.google.com/books?id=9WY6AAAAMAAJ&pg=PA227&a... ).
[Edited on 23-3-2013 by AJKOER]
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KonkreteRocketry
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How much concentration of HCl can i get, if i do this...
NaCl + 7% Acetic acid, then wait for few min for reaction, then put the bottle inside a -5 degree fridge to freeze the water and then pour the rest of
the liquid out..
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AJKOER
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| Quote: Originally posted by KonkreteRocketry | How much concentration of HCl can i get, if i do this...
NaCl + 7% Acetic acid, then wait for few min for reaction, then put the bottle inside a -5 degree fridge to freeze the water and then pour the rest of
the liquid out.. |
There are much much better paths to dilute HCl, but my initial thoughts on performing this particular experiment would be to add drops of vinegar to a
pile of NaCl sitting in a dish surrounded by a small amount of distilled water, all of which is in a closed container and partially crushed to allow
for expansion. Briefly heat the vessel in a microwave. The logic (speculation) is that any formed HCl gas is absorbed in the water and not returned to
the system (at least, not in the short run). Wait until all the fumes are gone, stir and/or replenish the pile of salt, and add more vinegar....
-----------------
Another embodiment would be to place some distilled water (or ice) in a balloon connected to a bottle placed horizontally containing an excess of salt
to vinegar. Heat in a microwave until max expansion of the balloon containing water. Remove and cool the balloon and recover the product.
In all embodiments, I expect the distilled water to contain some HCl (or none) and vinegar (from the heating and condensation).
[EDIT] I performed several experiments. First, I heated a small amount of vinegar in a partially crushed bottle (to allow for expansion) in a
microwave. To this upon opening, I added increments of salt, smelling after each addition. Interestingly, the smell of vinegar was sharply cut with
the addition of large amount of NaCl. I then reheated the excess salt/vinegar in a partially crushed bottle to expansion (plus a few seconds) and then
ran cold water over the top half of the bottle. I witnessed a surprising complete crushing of the bottle.
I repeated with plain water and also using plan vinegar, but in neither case was there such a magnitude of crushing. I also noticed that the bottle
reaches max expansion faster with the excess salt/vinegar mixture.
I repeated the experiment of heating an excess of salt with vinegar in a partially crushed bottle to expansion (plus a few seconds). This time, the
bottle cap popped off with a loud noise. I replaced the cap and ran cold water over the top half of the bottle. I witnessed a surprising crushing of
the bottle to about the original preheating size (remember, this was from a previously opened bottle).
Conclusions: The rapid expansion and contraction witnessed are in line with a gas (like HCl or a volatile acetic acid escaping from the brine
solution) formation that is highly soluble in water (which I was not able to distinguish, however, from the sharp smell of vinegar). I can only
explain the magnitude of crushing by assuming that the Hydrogen chloride (or Acetic acid vapors) formed pushed out some of the air, that is, the
bottled cap leaked under pressure, leaving largely gaseous HCl (or Acetic acid) and very hot water.
Also, the drops of vinegar to dry NaCl mixture should be heated for best results.
Note, on net no aqueous HCl was produced in this experiment as any formed would have reacted with the Sodium acetate. Also, no definite proof it was,
in fact, just HCl gas.
[EDIT][EDIT] I repeat again the experiment twice with a NaCl/Acetic acid mix and once with just Acetic acid. On heating in a microwave, again the
NaCl/Acetic acid mix bottle re-inflated the fastest. This time I held an ammonia solution to the neck of each bottle. In both cases, no NH4Cl smoke
ring visible. I then added a little aqueous ammonia to the bottle and push in, and I did witness repeatedly the formation of light smoke rings
(similar to what a tobacco smoker forms) with the NaCl/Acetic acid mix, but not with the pure Acetic acid bottle. As I observed, the rings were not
as intensely white as I have seen in the presence of chlorine, but still evident.
Revised Conclusion: Barring explanations to the contrary, one might conclude that a small amount of very dilute HCl was indeed produced. Most likely,
however, not a practical source of dilute HCl, but some may find the results theoretically interesting (and those who dismiss my conclusions are
welcomed to repeat this simple experiment for themselves).
[Edited on 23-3-2013 by AJKOER]
[Edited on 23-3-2013 by AJKOER]
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AJKOER
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It is still possible, however, that a small amount of condensed more concentrated acetic acid did react with the ammonia producing a white Ammonium
acetate salt, which could be responsible for the mild smoke rings, that I observed (I have not, as of yet, found any reports confirming this
speculation on the gaseous formation of Ammonium acetate). [EDIT] To quote this source (http://chestofbooks.com/food/beverages/A-Treatise-On-Beverag... ):
"3. Ammonia may be detected also by slightly acidifying the water with muriatic acid, evaporating to dryness and adding to residue some caustic potash
or soda solution. On holding the glass rod, previously dipped in acetic acid or diluted nitric acid, in close proximity to the residue, a thick white
fog will be visible. (Hager.)"
So acetic acid (of sufficient strength I would guess) and ammonia can produce a "white fog", which is apparently the white Ammonium acetate salt.
So the formation of any HCl (from heating a large excess of dry NaCl with vinegar) is apparently still not definite, IMHO.
[Edited on 23-3-2013 by AJKOER]
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KonkreteRocketry
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So is HCl produced actually in this reaction ? I asked my chem teacher who say it dosent happen ?
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Eddygp
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NaCl would dissociate more strongly in acetic acid solution than in distilled water, and the protons H+ that the acetic acid would give out could, in
a very small quantity, react with the chloride anions to create HCl, but I'm not sure if this could react noticeably (HCl would easily react with
sodium acetate to yield sodium chloride and acetic acid).
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DutchChemistryBox
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Maybe i'm stupid, but HCl is a strong acid.
So it has a Ka greater than 1.
So the conjugated base (which is Cl-) must have a Kb which is smaller than 10^-14.
I can't understand why the H+ wil stick to the Cl- when it has such a small Kb.
If you ask me, it isn't possible to create HCl with just acetic acid and NaCl
Correct me if I'm wrong
*i hope my englisch is readable*
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woelen
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If you add NaCl to acetic acid, then there will be an equilibrium reaction, but this reaction will be very strongly to the side of NaCl + CH3COOH.
CH3COOH + NaCl <<<<----> CH3COONa + HCl
In practice I think that the amount of HCl will hardly be observable, it will at best be formed in trace amounts.
This reaction with somewhat weak acids can be used to make HCl, if there is another driving force, which takes away the HCl from the system. An
example is heating of a mix of NaHSO4 + NaCl. NaHSO4 is a moderately weak acid, but it is stronger than acetic acid. If you heat a mix of NaHSO4 and
NaCl, then there is an equilibrium with Na2SO4 and HCl. Again, this equlibrium is quite strongly to the side of NaHSO4 and NaCl, but in the hot (e.g.
around 100 C) mix, the HCl is the only gas and then this gas can escape and in this way, the reaction is driven to the side of Na2SO4 and HCl. This
reaction is not a really practical method of making HCl, but enough HCl can be made in this way such that it is clearly visible (fuming).
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KonkreteRocketry
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| Quote: Originally posted by woelen | If you add NaCl to acetic acid, then there will be an equilibrium reaction, but this reaction will be very strongly to the side of NaCl + CH3COOH.
CH3COOH + NaCl <<<<----> CH3COONa + HCl
In practice I think that the amount of HCl will hardly be observable, it will at best be formed in trace amounts.
This reaction with somewhat weak acids can be used to make HCl, if there is another driving force, which takes away the HCl from the system. An
example is heating of a mix of NaHSO4 + NaCl. NaHSO4 is a moderately weak acid, but it is stronger than acetic acid. If you heat a mix of NaHSO4 and
NaCl, then there is an equilibrium with Na2SO4 and HCl. Again, this equlibrium is quite strongly to the side of NaHSO4 and NaCl, but in the hot (e.g.
around 100 C) mix, the HCl is the only gas and then this gas can escape and in this way, the reaction is driven to the side of Na2SO4 and HCl. This
reaction is not a really practical method of making HCl, but enough HCl can be made in this way such that it is clearly visible (fuming).
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Can i pour Acetic acid onto a hot salt plat ? it will touch the salt and like vapourize in seconds making the HCl escape before it goes back to NaCl ?
can i simply add salt + acetic acid and boil it for HCl to come out ? because it has a much lower boiling point and so much more likely to escape than
the acetic acid ? seems like a good idea ?
Than i can connect the whole thing to a tube and put the HCl gas into a water solution and ill get a HCl solution right ?
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woelen
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No, that will not work. Acetic acid and HCl are so far away in strength that the equilibrium is nearly 100% (i.e. 99.999...%) at the side of NaCl and
CH3COOH. If you pour CH3COOH on solid hot NaCl, then you just get a lot of acetic acid vapor and no HCl.
If you can't get HCl, then try to find so-called pH-minus (which is NaHSO4.H2O) and mix that with NaCl and heat this mix. The hydrated NaHSO4.H2O
melts in its own water of crystallization at 60 C or so and then it dissolves NaCl and on further heating, HCl will leave the mix fairly easily,
together with water vapor.
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