Endothermic reaction when mixing macros - The Planted Tank Forum
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post #1 of 3 (permalink) Old 02-10-2013, 10:24 PM Thread Starter
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Endothermic reaction when mixing macros

I had to mix up some dry ferts today. I used different bottles that were thinner than what I had before. I added 5tbsp. of KNO3, 1 1/4 tbsp. of KH2PO4, 20ml Excel (mistakenly) and 300cc of water. When I shook the bottles to mix, it became quite cold ; 53F from 74F in fact. I never noticed this before (thicker bottles I guess). Is this caused by mixing the KNO3 with water or what? I know cold packs mix ammonium nitrate, potassium hydroxide and water which produces KNO3 and ammonia gas but not sure if it works the other way around. Just curious.
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post #2 of 3 (permalink) Old 02-10-2013, 10:25 PM
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Yah, most of these salts absorb quite a bit of hit when mixed. Although some make things warmer. I think CaCl2's dissociation is quite exothermic.
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post #3 of 3 (permalink) Old 02-10-2013, 10:35 PM
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It depends on how the species is solvated and yes, CaCl2 is exothermic.
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