Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: bmore_ravens on 19/08/2012 09:49:35
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Does anyone know of a practical way to make hydrochloric acid at home?
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Does anyone know of a practical way to make hydrochloric acid at home?
NaCl + H2SO4 --> HCl + NaHSO4
HCl evolves as gas and you collect it, through glass pipes, inside water where it dissolves.
Instead of H2SO4 you can use NaHSO4, KHSO4, ecc, but you have to heat:
NaCl + NaHSO4 + heat --> HCl + Na2SO4
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It could be just a matter of interpretation, but I don't think that ticks the boxes marked "practical " and "at home"
Realistically, buy the stuff.
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You can purchase HCl as Muriatic acid which is often used for cleaning bricks. Check your local building supply store. I don't know the strength.
In another topic, (http://www.thenakedscientists.com/forum/index.php?topic=45184.0) you suggested using electrolysis to make H2 gas + O2 Gas + Cl2 Gas. If you capture, and re-combust and cool the gas, then you should end up with HCl. It might take some setup to make the combustion chamber, but perhaps it would be an elegant method.
This article discusses making gaseous HCl. (http://www.erowid.org/archive/rhodium/chemistry/hclgas.argox.html), which you could cool and add water to make the desired concentration of HCl.
BC is right though, you are trying stuff that perhaps should not be done in the garage.
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Thanks for the idea, but don't worry I never do any experiments that release gaseous substances in an enclosed area. Always outside.
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It could be just a matter of interpretation, but I don't think that ticks the boxes marked "practical " and "at home"
Certainly, not for kids or peple without the appropriate restraint. As a student, I began from this:
http://chemistry.about.com/b/2008/08/05/banned-book-the-golden-book-of-chemistry-experiments.htm
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It could be just a matter of interpretation, but I don't think that ticks the boxes marked "practical " and "at home"
Certainly, not for kids or peple without the appropriate restraint. As a student, I began from this:
http://chemistry.about.com/b/2008/08/05/banned-book-the-golden-book-of-chemistry-experiments.htm
Looks like a great book (for use with parental supervision).
Perhaps use it with your Handy Andy Science and Chemistry set.
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Most pool supply companies carry Muriatic acid. It is very cheap, I believe four gallons cost me, about twenty or thirty bucks. It was pretty cheap.
Sincerely,
William McCormick
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Does anyone know of a practical way to make hydrochloric acid at home?
They say if you create a container in the dark filled with chlorine and hydrogen gas 36 to 1 by weight, chlorine to hydrogen, and then expose it to direct sunlight, that it explodes violently. It used to be called Spirit of Sea Salt. Because they used Sea Salt to make it with sulfuric acid, like bmore_ravens had mentioned.
They say you cannot collect it over a vat of water. Because the water absorbs so much of the gas, something like 480 times the waters volume in gas.
Sincerely,
William McCormick
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Does anyone know of a practical way to make hydrochloric acid at home?
They say if you create a container in the dark filled with chlorine and hydrogen gas 36 to 1 by weight, chlorine to hydrogen, and then expose it to direct sunlight, that it explodes violently. It used to be called Spirit of Sea Salt. Because they used Sea Salt to make it with sulfuric acid, like bmore_ravens had mentioned.
They say you cannot collect it over a vat of water. Because the water absorbs so much of the gas, something like 480 times the waters volume in gas.
Sincerely,
William McCormick
This is a method, definitely not an appropriate method, for making hydrogen chloride gas. Do not try it anywhere.
Hydrochloric acid is the name of a solution of hydrogen chloride in water, so the uptake in water is an essential part of preparing hydrochloric acid.
A moderately safe method of preparation that would be suitable for home use, is the following: prepare a saturated solution of calcium chloride in water. That will involve roughly equal masses of the hydrated salt and the water. The solution will be roughly 7 M in calcium, 14 M in chloride. Then add sulfuric acid. Bench dilute sufuric acid is often about 6 M, so if that is used you would use a volume about 10% larger than the volume of your calcium chloride solution, and you will obtain a precipitate of calcium sulfate, which is only sparingly soluble.
Filter this off, and you will have a hydrochloric acid solution of about 6M concentration. It will be contaminated with dissolved calcium sulfate (solubility roughly 200 mg/L) and either calcium chloride or sulfuric acid, depending on the stoichiometric balance in the reaction, and how closely you have judged the quantities. I could think of no suitable indicator for the endpoint of the precipitation reaction.
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A moderately safe method of preparation that would be suitable for home use, is the following: prepare a saturated solution of calcium chloride in water. That will involve roughly equal masses of the hydrated salt and the water. The solution will be roughly 7 M in calcium, 14 M in chloride. Then add sulfuric acid. Bench dilute sufuric acid is often about 6 M, so if that is used you would use a volume about 10% larger than the volume of your calcium chloride solution, and you will obtain a precipitate of calcium sulfate, which is only sparingly soluble.
Good method, damocles! And using NaHSO4 instead of H2SO4, is even safer.
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Thanks for the compliment lightarrow. I must point out though, that although safer, the NaHSO4 method is not appropriate because (1) NaHSO4 is not very soluble (similar to NaCl on a mass basis, and only about 2.5 M saturated solution), and (2) the final solution would contain just as much NaCl as HCl.
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True, but you could distil it.
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OK, some more thoughts on this one.
Firstly, I should have said not to use concentrated (98%) sulfuric acid on this one. Battery acid (around 10 M) is the strongest sulfuric acid you should consider using, and bench dilute sulfuric acid (6 M) is ideal. Sulfuric acid is highly corrosive, and at higher concentrations it will generate a lot of heat when mixed with water. Be very careful if you are using sulfuric acid.
On the other hand, that also applies to the hydrochloric acid that you will be producing -- not quite, but nearly to the same extent.
If you decide to use the sodium bisulfate method, you need to use about 3 volumes of saturated bisulfate solution to 1 of saturated calcium chloride. If you filter the product, you will obtain a solution around 2M in hydrochloric acid and 2M in sodium chloride, along with 200mg/L calcium sulfate, and a small excess of either calcium chloride or sodium bisulfate.
If, on the other hand, you choose to distil the product, you could obtain uncontaminated 11 M hydrochloric acid solution, but the procedure would require a distillation apparatus, and it would increase the potential dangers to well beyond those of handling moderate concentration sulfuric acid solutions. One of the advantages of the method I proposed was that it would cut out any need for distillation, and the specialized apparatus it would require, and the extra potential safety problems it would introduce.
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But with the method you proposed you still need distillation, if you want pure concentrated HCl, because CaCl2 and H2SO4 should be in dilute solution; otherwise you will have also some Ca(HSO4)2 dissolved in water:
2HCl + 2CaSO4 <--> Ca(HSO4)2 + CaCl2
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But with the method you proposed you still need distillation, if you want pure concentrated HCl, because CaCl2 and H2SO4 should be in dilute solution; otherwise you will have also some Ca(HSO4)2 dissolved in water:
2HCl + 2CaSO4 <--> Ca(HSO4)2 + CaCl2
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Good point, Lightarrow. I am rather embarrassed now. The endpoint of the reaction I had originally proposed envisaged a 6 M HCl solution with a calcium sulfate precipitate and a 200 mg/L calcium sulfate contaminant in the solution. I had completely overlooked the sulfate/bisulfate equilibrium, which, at pH -0.8, is very much tilted towards bislufate.
So there are three pretty much equivalent methods:
(1) concentrated sulfuric acid on solid sodium chloride
pro:
-- cheapest and least wasteful of materials
-- does not require active distillation
con:
-- involves a very dangerous material
-- requires an airtight gas line and bubbler for collecting HCl gas and dissolving it in water
-- totally unsuitable for home/garage use
(2) bench dilute or battery sulfuric acid on saturated calcium chloride:
pro:
-- reasonably safe materials, though caution and handling expertise still required. The safety issues with handling battery acid are similar to, and of the same magnitude as those with handling an 11 M hydrochloric acid product.
-- efficient use of relatively cheap and available materials
con:
-- distillation apparatus and setup difficult for home/garage situation
-- distillation process introduces new safety issues and requirements for handling expertise.
(3) saturated sodium bisulfate with saturated calcium chloride
pro:
-- safest for handling starting materials
con:
-- distillation issues as in method (2)
-- wastage of much of the starting material
-- starting materials more expensive and less readily available? (I do not know about Britain/US; is certainly the case for sodium bisulfate in Australia)
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Good point, Lightarrow. I am rather embarrassed now.
You shouldn't, we are here to discuss and I have learned a lot from you posts [;)]