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Author: Subject: endothermic ammonia formation, liquid ammonia?
Antiswat
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[*] posted on 5-5-2019 at 07:23
endothermic ammonia formation, liquid ammonia?


i remember seeing barium hydroxide and ammonium chloride used to demonstrate highly endothermic reaction, been for years unable to find exact temperature drop this can cause but i believe i heard -70*C at some point

Ba(OH)2 + NH4Cl = NH3 + BaCl2 + H2O

now this wouldnt be entirely anhydrous, but likewise Ba(NO3)2 + H2SO4 and then using a very fine glass filter with teflon coated vacuum pump it should be possible to extract, maybe use something to soak up the water from the reaction and thereafter use perfectly anhydrous CaCl2 to absorb the ammonia?

the low temperature created with thie reaction is whats making it so much more interesting than, for instance decomposition of ammonium carbonate, tho the CO2 from that wouldnt be much difficulty dealing with, but that would add heat as well




~25 drops = 1mL @dH2O viscocity - STP
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https://en.wikipedia.org/wiki/Solubility_table
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vmelkon
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[*] posted on 6-5-2019 at 09:27


Do you want to make liquid ammonia?
I doubt that you would be able to achieve -70*C. It would probably be more like -15*C.
I think they use Ba(OH)2 and NH4NO3 in class demonstrations to show that you can freeze water.

In a home brew setting, an easy way to do it is to invert a propane tank and let the propane come out. The bp of propane is -42*C, which can be used to cool NH3 and have a little bit of liquid NH3.




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[*] posted on 6-5-2019 at 17:14


In my opinion more simple is using of dry ice/acetone bath.
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Antiswat
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[*] posted on 22-5-2019 at 03:08


its actually a heck lot more easy to just buy liquid ammonia, not that everyone can buy that, but thats besides the point of simplicity.

ok so a bit of digging people suggest it reaches around -25*C
but knowing that kelvin is the true temperature and celcius is only relative to STP.. performing this in a freezer which typically reaches -18*C, wouldnt this mean that it could potentially reach down to -33*C which is the boiling point of ammonia? -18 to 20*C would be a total of 38*C taken out of the equation
i dont like spending chemicals, always cringed at the vacuum generator using high pressure tap screw attachment (nurdrage found a way to use this without it wasting water, waterpump in a bucket)




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
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