resonance
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Safrole Enthalpy and Entropy ??
Safrole Enthalpy and Entropy ??
does anyone ahve any idea what these are , how i could work it out or where i could find this info ???
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daeron
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i knew ol thermo would come back to haunt me
you can calculate them but its a pain in the arse imo.
if you go by foot you first have to calculate Tc,Pc and such using forman-thodos,riedel,lyndersen and simillar criterias than you have to use these to
calculate the enthalpy and entropy values.
or you can use souders-matthews and hurd,verma-doraiswamy or anderson-beyer-watson criterias to calculate the Cp,H,S values,and these will be the gas
state values so youll have to make corrections,etc....as i said a pain in the ol arse
you can calculate them using programs like aspen,too.
and at the end these values wont be so correct,they all have some degree of error...even the ones you would dig out of the thermo handbooks.
i hope this well kinda helped
PS what do you indend to do w them?you are aware that the most of the calculations using these values will be waaay off in comparison to the real
system,since you will have to make some shortcuts.....either way good luck
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docberto
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It would be much easier to look up that sort of thing in the CRC tables.
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daeron
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yup..well maybe but still inaccurate..
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praseodym
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Safrole
3,4-methylene-dioxyallylbenzene, C10H10O2
Safrole has been declared carcinogenic by the FDA, and human consumption is banned.
Melting Point: 11.2
Boiling Point: 232
Solubility: Insoluble in water
And...entropy and enthalpy are stuffs of thermodynamics.
Enthalpy is given by the equation H=E + PV. It has something to do with the 1st law of thermodynamics. Enthalpy is most useful when pressure is held
constant through exposure to the surroundings, to analyse reactions that increase the volume of the system, causing it to do mechanical work on the
surroundings and lose energy. Conversely, reactions that cause a decrease in volume cause the surroundings to do work on the system, and an increase
in the energy of the system. It makes sense to treat the enthalpy as a measure of the total heat in the system, so long as the pressure is held
constant. For an exothermic reaction at constant pressure, the system's change in enthalpy is equal to the energy released in the reaction,
including the energy retained in the system and lost through expansion against its surroundings. Similarly, for an endothermic reaction, the
system's change in enthalpy is equal to the energy absorbed in the reaction, including the energy lost by the system and gained from compression
from its surroundings.
On the other hand, entropy is a measure of the amount of energy in a physical system that cannot be used to do work. More generally entropy is a
measure of disorder/randomness. If a subsatnce is undergoing a reversible change takes in a quantity of heat dQ at temperature T, dQ/T is then the
increase in entropy of such processes. Increase in entropy is accompanied by loss of available energy in a system. Hence it follows that the processes
that involve an increase of entropy of the material universe also involve a loss of available energy in the universe. The entropy of the universe
tends to a max that will be reached when all temperatures differences have disappeared. The available energy in the universe will then be exhausted
(2nd law of thermodynamics) and the universe will suffer, a 'Heat-death'. Only changes of entropy are significant, indicating the change of
state of a system. For more info on enthalpy and entropy, look up on thermodynamics and Boltzmann's Principle as well.
Hence i conclude that safrole enthalpy and entropy are the enthalpy and entropy of safrole.
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neutrino
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What exactly was the point of that post? I think I missed something...
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sparkgap
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Maybe he ought to have been specific about what he wanted, right? Did he want the enthalpy of formation, enthalpy of mixing, enthalpy of vaporization,
enthalpy of... well, you get the idea. 
sparky (~_~)
P.S. A similar question was why I was asking if anyone had a copy of Landolt-Bornstein (only one "d" in Landolt, sorry) a while back...
Please oh please, can someone add it to our FTP's if they chance upon a nice copy?
[Edited on 1-8-2005 by sparkgap]
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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docberto
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From his post enthalpy and entropy of formation would seem to make the most sense.
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praseodym
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Ya, i agree that the question is vague. If he is asking for safrole enthalpy and entropy, i guess he is asking for the enthalpy and entropy of
formation of safrole...
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sparkgap
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praseodym:
Eh, WTF were you on to again?  
You just repeated what you said in your first post of this thread! 
I don't think there was a point, neutrino.
docberto: OK, formation... from what? Which reactants? You know very well that there's more than one way to tap a sassafras bush...
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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resonance
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i wnated to know for a chemistry reaction modelling prog im testing out...
when im adding a new species i need the following paramaters:
molecular weight
density
standard enthalpy of formation
standard entropy
standard state (liquid, gas, or solid)
it's only theoretical and doesnt need to be precise or that accurate...
so any help or guestimations would be greatly appreciated !
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daeron
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| Quote: | Originally posted by sparkgap
docberto: OK, formation... from what? Which reactants? You know very well that there's more than one way to tap a sassafras bush...
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Um err like THE enthalpy of formation,yknow basic thermo…tz..tz got nothing to do w the way you acquire sassy..
Resonance- its best you start w the basic equation of states,than you calc the Cp and from there go to the Hs and Ss.youll get a better model and it
easier,standard H of formations would still be needed,though.
Are you writing your own prog(in matlab fortran,whatever) or are you using some package?ive spent the quite some time yrs on working these
topics(chem reactor/rxn modelling) so maybe I can be of some assistance...
and btw those data you need isnt const,so its better you use some empirical equations for density,states,H,S,etc
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sparkgap
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Tsk, you got lost in my wording. Sorry for that. 
Isn't it supposed to be that you need the basis reaction reactants-->safrole when computing the enthalpy of formation? There is more than one way to make safrole, AFAIK, in the same way there's more
than one way to tap a sass bush. That's what I meant.  My apologies.
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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resonance
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I am just looking at a program called "virtual chemistry lab" (freeware) ... id love chem lab but I can only get trialware
as you've prob caught on now, id like to add my own chemicals and reagents to one of these programs and set up some "practice" work-ups
for processes , primarily for fun and familiarisation, rather than absolute accuracy or testing/modelling.
if you or anyone could help out by recommending or sampling me some some software , working these parameters out , or showing how to, it would be
greatly appreciated
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daeron
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sparkgap -no need to apologize-the standard enthalpy of formation is the same(in theory,of course) and doesnt depend on the route of synth-look up
hess law.actually i think all the standard Hs of form. are accqured by -and dont hold my word on this- measuring the "heat effects" during
the thermal decomposition of a certain compound.eg safrole to C,O2 and H2 but you can go as far as CO2 and H20 since their Hs are well known.
resonance-im not fammiliar w that prog,but usually the best programs for calc properties&chem rxns are chem.eng progs.i work w aspen but if you
have the money to buy it that youre a millioner or you just work in companies like basf,exxon,etc.there are still some good progs out there i forgot
the name of the software company but i think that name of one of their products was mixprops or something.the two others that pop in my mind are
chemcad and chemshare but those are more chem.eng progs and component properties are calculated before you even start doing anything serious w them.
if youre really into learning and understanding the basics on which these progs work you should look up the thermo criterias i postes here,since their
variations are used in those progs.in fact some of those calculations are so simple you can make your own prog in matlab or fortran and often the more
serious chem calc progs even require you to do so,or to make some sort of imput.
as for the classic chem progs i would have to ask a friend and report back,but most of the time all the things you can do w them you can also do w
afore mentioned progs....i hope my incohernet writting helped a bit..
[Edited on 1-8-2005 by daeron]
[Edited on 1-8-2005 by daeron]
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praseodym
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Sorry, sparkgap. I was just trying to help with the question. Apologise for any
offence
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praseodym
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Maybe i misinterpreted the qn. Sorry again
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resonance
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ok, i really liekd the idea of people making practicle examples of reactions for a lab sim software, that nub's could have a go at... where you
have a wrokbench and you set up you reflux , ad your stuff and ...
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