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Author: Subject: Delta Heat of Formation question
Formatik
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[*] posted on 24-10-2008 at 23:53


Why include the heat of formation of water? The book cited above only mentions the solute being computed into the Hf value at the certain concentration.

For example, the energy of -45.54 kcal/mol forms per mol equivalent of H2O2 although diluted throughout the rest of the water medium in its formation.

I think we get that what the 30% forms per gram is obviously different since the entire water amount is now taken into consideration. The energy dissipates throughout the water. But this absorption is also irrelevant to any calculations here.
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[*] posted on 25-10-2008 at 01:13


To make clear what I'm saying. The only way I can think to make sense of the results of that program is to assume the heat of formation is just the peroxide per the entire gram of the aqueous peroxide solution, as opposed to just the equivalent kcal/mol or g, which gives results close to pure peroxide.
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Hydrazine
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[*] posted on 25-10-2008 at 05:11


OK. I see now.

This table is not applicable to my application. At least not directly.
It is a table of only the peroxide in the solution. Not the solution as a whole. Damn.

OK, so I can see a way to find the answer using the data in this table, but it will be a tedious conversion process.


If I average the heat of formation with water, I will also have to manually average the O and H atomic composition per gram of solution!:o Yikes. :o This will take a while.

This will be fun because I will also have to interpolate all values of peroxide solutions in the 30-50 percent range by 1% increments. (I need to dial in an optimum concentration for the end use)

Thank you for your help guys and gals! :D

PS Formatic - Yes, I have to include the heat of formation of water because it all goes into the same reaction chamber where it is intimatly part of the reaction process.

[Edited on 25-10-2008 by Hydrazine]
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[*] posted on 30-10-2008 at 08:46


I've found this program called GDL Propep, is that anything as good as Propep?

The program gives a value of 164.5 Isp for pure H2O2. The reported is about 163. For 70% though, the value is 179.1 Isp. I changed it to use proportions and then the result for 70:30 was a more realistic 109.4.
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