04-21-00 05:11
No 108461
Author Topic: OTC HCl gas
Piglet
Member posted 08-05-98 04:44 AM
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2NH4Cl + H2SO4 -----> 2HCl + (NH4)2SO4
this came to me last night. Swap the H2SO4 for NaOH and you got an NH3 generator (thats where I nicked the idea from).
Doesn't work with HCl below 37% very well. [Got this from J. Chem. Ed.] J. Chem. Ed. 1995, page 1139. Summary: "In a typical run, 100 g of 35% HCl were added on to 100 g granular CaCl2 (anhydrous) at room temperature (thermal effect is insignificant) and 15 g of HCl(g) were obtained. This represents over 40% yield. But the CaCl2 produced may be dehydrated by heating at ~ 200 C to give anhydrous CaCl2 again. The small amount of Ca(OCl)2 formed in this way is ignored. Mmm. Sounds better to use concn. H2SO4 and NaCl to me.
Piglet
Member posted 08-05-98 06:40 AM
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Actually, H3PO4 should be even better...
But what governs the production of hydrogen carbonates? H2NH4PO4 etc?
Piglet
Member posted 08-05-98 11:05 AM
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Actually, boric anhydride is rather easy to make from borax (as bought OTC), What would happen in this case?
Cherrie Baby
Member posted 08-06-98 08:49 PM
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Anhydrous CaCl2 + HCl (37%) also works to give HCl gas.
When reaction is over just heat residue liquid to regenerate anhydrous CaCl2.
Piglet
Member posted 08-07-98 04:08 AM
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The fact that HCl & H2SO4 are both listed is rather gauling. I wonder if you can use some handy OTC salt to strengthen up the HCl. Magnesium Sulphate (AKA Epsom Salts)?
Piglet 
Cherrie Baby
Member posted 08-18-98 07:10 PM
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Well I meant that it didn't work with 31% HCl as well but of course it'll work.
"A convenient way to generate hydrogen chloride in the freshman lab. F J Arnaiz
