EdricoRojo
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Questions regarding understanding stoichiometry
Hello all. I have been lurking here for a while. I just made a account as I have a number of questions that I can't seem to find the answers to.
I have a interest in energetics, I have successfully synthesized and detonated a number of different materials. While looking for methods of
manufacture, it was often said throughout the forum to not use "recipes" but to come up with methods of manufacture oneself.
So, I thought that was interesting. So I have been trying to find out how to figure out the stoichiometric ratio to do a process.
On this board it has been mentioned that scaling affects the ratios of materials in a synthesis. How is this true?
I come from a automotive background, the stoichiometric for air and gasoline is 14.7-1. that is the same whether it is a 1L motor or 8L. I have made
ETN and scaled it up a little using the 1-4-10 ratios with AN. My results have been excellent regardless of whether it was .5oz, or 10oz. The main
variable is temperature control.
My apologies if I am not as clear as I think I am lol. I learned about molles as it was alluded that they were the secret. Yeah they are a important
measurement, but just that. I hope my question(s) weren't to broad. If you point me at a video to explain the process that would be excellent as well.
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Pumukli
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With energetics the variable stoichiometry MAY mean that a small ammount of energetic material will detonate differently in different geometries. To
compensate for this behaviour one may alter (slightly) the basic stoichiometry which is given for e.g. a much larger charge.
Or, during preparation, there are definitely differences of thermal behaviour and which is possible in a small batch may be fatal if repeated on a
larger scale. (Thermal runaway.) To compensate for this difference one may have to alter the stoichiometry e.g. by using more solvent.
Beyond this I doubt that there is any variability in stoichiometry in these types of materials. Moles are moles, regardless of the compound they
represent.
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charley1957
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YouTube has dozens of stoichiometry videos, practice problems, etc. Lots of different teachers and different ways of teaching it.
You can’t claim you drank all day if you didn’t start early in the morning.
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EdricoRojo
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Thank you very much for the replies and clarification.
I did watch a number of videos on stoichiometry prior to asking. Tried doing my legwork as best I could figure out.
@Pumukli That is a very interesting thought on changing ratios to prevent thermal runaway. I tried doing a small nitration with the method of freezing
the AN/H2S04 then mixing the Erythritol. That worked great. When I did a larger volume (gallon jar) the behavior completely changed. The nitration
didn't occur until after the AN/H2S04 had warmed to about 25c. Then at that point it accelerated the nitration. Which by putting the glass container
in water and stirring the composition I kept it under control and had excellent yield.
So in a basic nitration, you are suggesting using more solvent, which in this case we are using the H2S04. and that will maintain the same amount of
nitrate to material that needs nitrated, but in a semi dilute fashion, and thereby have a slower nitration process, which would mean less time for the
heat to build and more heat to exhaust.
I would assume that the same concept applies when using nitric acid as well then.
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Sulaiman
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As a casual hobbyist, when I was new to SM, I quickly discovered that many members discourage following or requesting 'recipies',
which seems logical as experimental science, doing your own research, is the focus of SM, from noobs to cooks.
I now realise that the bulk of chemistry IS recipes.
. stoichiometry is great!
.. IF you know all possible side reactions and can calculate likely yields under various conditions
.. well known (and feared) thermal problems varying with scale
.. even the sequence or speed of combining 'ingredients' can be critical.
I love it!
CAUTION : Hobby Chemist, not Professional or even Amateur
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RU_KLO
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The problem with recipes is, probably, that they are not well written (they skip procedures or they dont take into account that someone does not have
the corresponding knowledge (they assume "common" chemistry knowledge).
For example:
Dilute concentrated sulfuric acid with water to an xxx amount. (if you never diluted concentrated H2SO4, you maybe add xxx amout of water to the acid
and then you have a acid mist/splashing in your face....)
Patents are not always complete, there are some details preserved, to avoid copying it.
Also there are some rubbish recipes or claims.
Like some said, in chemistry the devil is on the details (something may seem simple, but in fact the details are complicated and likely to cause
problems.)
If I want to do something new, I check for recipes, but from different sorces and from indirect subjects that may give 1 or 2 hints about the reagents
or procedures used in the recipe.
Go SAFE, because stupidity and bad Luck exist.
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EdricoRojo
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I had noticed a marked lack of important information for noobies in some literature that I have read that can VERY well end disastrously! Which it did
appear to me when starting out that it did all come down to "recipes", which then just confused me when folks said not to follow recipes lol. I do
like the video format of learning as you can watch the process and if it is a good teacher, often learn the why of things, not just the ratios and
process. Which in print is usually just omitted just because it is assumed that you know what your doing.
I am really interested to mess with ratios on some more nitrations, and experiment there. I have made some HMTD before I found this forum and its
severe anti peroxide teachings for noobs, which is justified. Which I found out through trial that it is the most unstable when it is not washed well
and is sticky. Side note (from a side note) I am going to use different detonator material, have tried CHP66 before, and am going to try CHP.
The cross referencing a project from multiple angles is kind of what I have ended up doing. Which these posts are kind of a part of that, as I figured
if there was some secret of stoichiometry I needed to learn, it would be good to pick that up before doing the next project. I will probably
experiment with the ratios on ETN a bit, as it is still a fairly "basic" process. less variables and what. Just because I am really interested in
seeing what the additional sulfuric acid will do to the temperature stability.
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EdricoRojo
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Here is a video link for anybody asking the same questions as me. This guy covers calculations. Just putting it here for future people.
https://www.youtube.com/watch?v=I_O-4M0_dsM
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EdricoRojo
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Just finished watching that video and before I could download, the channel was wiped clean. Here is the link to Odyssey. https://odysee.com/@DuganAshley:e/Advanced-Explosive-Design-...
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Random
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It is not so easy to understand that. I was already doing not that simple experiments even before I learnt stoichiometry.
Yes. It is hard to learn anything.
At least few people who taught me here are according to some indications no longer with us.
...
I would write Chemistry papers if I had the time.
Yes, its true. It is hard to learn Chemistry because it is also hard to find literature and experience... if you mess it up you die.
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Moles yes. If you want to learn Stoichiometry learn about Moles.
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Unfortunately I did not have time to read whole topic.
I learnt moles in 2011 according to my personal memory. A lot of it became easier then.
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Edit:
I would write a book on it if I had Time.
[Edited on 28-9-2024 by Random]
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