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AP to KP conversion


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#1 Powderman

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Posted 12 October 2021 - 07:20 AM

Most modern star formulas call for KP (KClO4) but AP (NH4ClO4) is the closest I was able to obtain. However it seems converting to KP should be "easy" - at least in theory. I have calculated that 170g AP dissolved in half litre of boiling water combined with 108g KCl also dissolved in half litre of boiling water gives cca 200g KP dissolved in litre of boiling water. Solubility for KP in boiling water is 210,8g so it may stay dissolved. After lowering of temperature down to 0°C less than 8g KP would stay dissolved and the rest should crystallize out. 

First question is if dissolving AP in boiling hot water is safe, and second one is if there is something important I overlooked?



#2 Mumbles

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Posted 12 October 2021 - 02:12 PM

I think that sounds fine.  When you filter the solid off, you'll probably want to rinse it a few times with cold water.  Ammonium chloride is pretty soluble, even at cold temperatures, so it should be removed fairly well.  The starting materials also are decently soluble, so any incomplete reaction or remaining material should be washed away.

 

One thing to note is that ammonium chloride may decompose in boiling water when it's formed.  The solid starts subliming/decomposing around 65C.  It does decompose slowly in boiling water as well.  Even room temperature solutions of it often have a mild odor.  You may get a face full of ammonia and HCl if you're standing close.  Needless to say this needs to be done in a well ventilated location.  Doing this at a slightly lower temperature may be advisable, maybe 50C.  This could even be done at ambient temperature using solutions of each, but the yield probably wont be quite as good of a yield.

 

I will say, I've never actually done this transformation.  For people in the US, it's generally ammonium perchlorate that is the harder to get material. 


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#3 Powderman

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Posted 12 October 2021 - 03:12 PM

Thank You very much for valuable info. I allways try new things at very small scale, but it really helps to know what I should expect. With the hot process I was besides good yield hoping to have crystals big enough to filter and rinse easily. Instantly formed precipitants tend to be very fine. Cooling rate is easy to control and so is the crystals formation. If the test fails because of ammonium chloride decomposing I will try different approach at only slightly elevated or room temperature by adding one solution very, very slowly (maybe even drop by drop) into the other while stirring to avoid instant precipitation leaving the crystals enough time to grow... After all is mixed I can continue with cooling to zero Celsius. Or maybe lower, I guess ammonium chloride solution will not freeze at zero.



#4 davidh

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Posted 13 October 2021 - 06:39 AM

If you give me your AP, I will convert it 1-to-1 to KP and give it back to you. What more could you want? I offer the same service converting gold to silver, 1-to-1.:-)


Edited by davidh, 13 October 2021 - 06:40 AM.


#5 Powderman

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Posted 13 October 2021 - 10:28 AM

If you give me your AP, I will convert it 1-to-1 to KP and give it back to you. What more could you want? I offer the same service converting gold to silver, 1-to-1.:-)

That would be great, but only if You were from the same small country in EU as I am... But thanks for the offer :-)



#6 Richtee

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Posted 13 October 2021 - 01:09 PM

If you give me your AP, I will convert it 1-to-1 to KP and give it back to you. What more could you want? I offer the same service converting gold to silver, 1-to-1.:-)

OK  dat’s majorly amusing :D


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#7 Powderman

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Posted 16 October 2021 - 11:55 AM

So I tested the reaction today and even when boiling (in glass test tube, I have recalculated everything to use only 2ml of water) no sign of smelly HCl or NH3... Crystals are growing right now, tube is inserted in some thermally isolating material to slow down cooling - I want to see the shape of the crystals formed :-)

I will probably heat it again and then let it cool while stirring to get smaller crystals not stuck to the bottom. Would be nice to find out how fast/slow the cooling should be done to have crystals of desired size.

Update - crystals sre not stuck to bottom or each other... I have made some calculations and if I am right the remaining solution (mostly NH4Cl) should not freeze until at least -5°C...


Edited by Powderman, 16 October 2021 - 12:46 PM.





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