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Author: Subject: Generating gases from OTC materials
alchemizt
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[*] posted on 9-2-2022 at 18:44
Generating gases from OTC materials


I built a gas generator with glass bottles and tubing and I really love how this simple device enables you to create new compounds from readily available every day materials. So far Ive only made a few things to test it out.

1.) Hydrochloric acid by mixing H2SO4 with NaCl and bubbling the HCl gas into water

2.) Ammonium hydroxide by mixing dilute NaOH with ammonium sulfate and bubbling the NH3 into water

3.) Cl2 gas by mixing dilute HCl with calcium hypochlorite.

4.) H2 gas by mixing NaCl solution with aluminum foil.

Can you mention a few other gases you can make with readily available OTC materials and some things you can use the gas for?

[Edited on 10-2-2022 by alchemizt]
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B(a)P
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[*] posted on 9-2-2022 at 20:18


Peroxide with an iron salt will give you oxygen (O2).
Acetylene from calcium carbide and water.
Nitrous oxide from the decomposition of ammonium nitrate.

Edit

Also Woelen's web site is well worth a look if you have not already.
Woelen web site

[Edited on 10-2-2022 by B(a)P]
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Amos
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[*] posted on 10-2-2022 at 07:19


You can make a stream of SO2 gas from sulfuric, phosphoric, or hydrochloric acid dripped onto sodium metabisulfite (homebrew sanitizer, stump remover)

CO2 is easily made by dripping any acid onto sodium carbonate or bicarbonate. Usually you want stirring in the gas generation chamber so it doesn't foam too badly. My choice of acid here is 80% formic acid since it has such a dense concentration of H+ ions.

My favorite method of making Cl2 is dripping HCl onto warm, wet potassium permanganate instead of chlorine-containing bleaches/chlorinators.

While it doesn't matter for every use, keep in mind that in many cases you will want to scrub the gas generated to remove moisture or unwanted volatile substances. Like in the case of making SO2 or Cl2 from hydrochloric acid, you should take steps to exclude HCl vapor if it presents any side reactions or changes the pH of your reaction too much. Water can often be removed from gas streams by bubbling them through concentrated sulfuric acid.
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yobbo II
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[*] posted on 10-2-2022 at 08:45




CO2 from fermenting

CO from hot charcoal with air restricted (may get CO2 as well though)
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[*] posted on 10-2-2022 at 08:56


Quote: Originally posted by alchemizt  


4.) H2 gas by mixing NaCl solution with aluminum foil.

[Edited on 10-2-2022 by alchemizt]


How does this work? Is the aluminum just reacting with water after the Al2O3 layer somehow dissolves?




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[*] posted on 10-2-2022 at 09:04


Sulfur dioxide from sodium metabisulfite and acid. Hydrogen sulfide from sulfide salts and acid, or from elemental sulfur and paraffin wax. You have to be careful if you make these though, because they are toxic, especially the hydrogen sulfide. If you plan to use them, make sure and read up on the best safety practices discussed here on the forum.



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[*] posted on 10-2-2022 at 22:42


Quote: Originally posted by sauveurdumonde  
How does this work? Is the aluminum just reacting with water after the Al2O3 layer somehow dissolves?


I believe it is a little complicated the way this works, and somebody correct me if I am wrong.
(I am not balancing anything)
In aqueous conditions the Cl ion will attack the aluminum forming AlCl3 and NaOH and H2. The NaOH then reacts with the AlCl3 reforming the NaCl and Al(OH)3, which then reacts again with the salt.

But doesn't this need another catalyst? I mean NaCl even in aqueous solutions doesn't react that fast with aluminum from my understanding, which is why we really have minimal concern cooking with aluminum pots, or is that something to do with oxidation layer that works as a passivization layer against the salt.

[Edited on 11-2-2022 by Syn the Sizer]

[Edited on 11-2-2022 by Syn the Sizer]

[Edited on 11-2-2022 by Syn the Sizer]
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woelen
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[*] posted on 11-2-2022 at 03:29


Al-foil with solution of NaCl gives no reaction. If you add a little CuSO4 or CuCl2 to the NaCl, then you get a quite violent reaction, with formation of H2, and very impure insoluble Al(OH)3. You even get a more violent reaction if you add Al-foil to somewhat acidified solution of NaCl, to which a copper salt is added. The copper salt is essential for a fast reaction, unless the acid is concetrated. In concentrated HCl without copper ions, Al-foil quickly dissolves, but only after a certain lead-period, in which the speed of the reaction slowly increases.



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[*] posted on 11-2-2022 at 08:39


Quote: Originally posted by woelen  
Al-foil with solution of NaCl gives no reaction. If you add a little CuSO4 or CuCl2 to the NaCl, then you get a quite violent reaction, with formation of H2, and very impure insoluble Al(OH)3. You even get a more violent reaction if you add Al-foil to somewhat acidified solution of NaCl, to which a copper salt is added. The copper salt is essential for a fast reaction, unless the acid is concetrated. In concentrated HCl without copper ions, Al-foil quickly dissolves, but only after a certain lead-period, in which the speed of the reaction slowly increases.


That makes sense, I was pretty sure that just NaCl would have little to no reaction not only because I have cooked salty soup in aluminum pots with no reaction, but Na is less electronegative then Al so there would be minimal displacement of Cl ions from Na to Al.

My assumption of how this proceeds is that the aluminum will reduce the copper salt to copper metal forming the aluminum salt, which in return gets attacked by H2O forming the crude Al(OH)3 and the respective acid, this acid then catalyzes the further reaction with NaCl.
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[*] posted on 11-2-2022 at 11:14


NaCl does not react with aluminium. Period. Sodium ions are not reduced to sodium metal, and metals are not oxidizers, so there is nothing aluminium could do to react with chloride ions. It serves as a source of chloride ions, which through a mechanism unknown to myself disrupt the continuous oxide layer that makes bulk aluminium metal less reactive than its reduction potential would suggest. Water and oxygen will react with aluminium with the addition of sodium chloride, but not in a fashion rapid enough to generate meaningful amounts of hydrogen. NaOH reacts vigorously with aluminium because it dissolves aluminium oxides at the surface forming water-soluble sodium aluminate, exposing the metal to react with water and hydroxide ions, yielding hydrogen and more aluminium oxide/hydroxide. Aqueous acids behave similarly, dissolving the oxide layer and exposing the metal to water and hydrogen/hydronium ions, which oxidize the aluminium while being reduced in turn to hydrogen gas.
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[*] posted on 11-2-2022 at 13:55


https://www.youtube.com/watch?v=QJjIBjB9i5Y

But is the NaCl a catalyst then, it is the copper salt and aluminum reacting to form the H2 gas isn't it, and it would only react until the copper salt is all used up.
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