• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

Reaction Kinetics

J

joe360

Senior member
I was just wondering if anyone knew a good place to find reaction kinetics. My product is Nitroglycerin and my reactant are nitric acid and glycerol. The kinetics that i am looking for is activation energy, rate constant and stuff like that. I have searched all over including google scholar and google patent and haven't come up with much. any help would be appreciated. the reaction looks like this: (sometimes sulfuric acid is used as a catalyst)

glycerol + 3 HNO3 ------> nitroglycerin + 3 H2O
 
I'm pretty sure its against Anandtech policy to help people try to develop explosives and other dangerous chemicals.
 
I thought HYSYS might have the information in their databases... If not, then what good is it? There are similar programs that have all of this data built in so you just name the species and it knows everything else. I think the program that I used for my senior design project was ChemCAD and I know it had all kinds of this information built in.

But, since I assume you're not an idiot, you probably already noticed that HYSYS didn't have it. I would check some chemistry/chemical engineering handbooks, such as the CRC or Perry's. I just checked through all of the appendices of my textbooks with no luck, and I don't have time to wade through Perry's right now. If you do find a database with this kind of information, let me know.
 
Do you have information on the amounts wouldn't be that hard to calculate Ea, and k if you had the amounts
 
Originally posted by: atchon
Do you have information on the amounts wouldn't be that hard to calculate Ea, and k if you had the amounts
Click to expand...
😕 Ea and k are intrinsic thermodynamic quantites - they don't depend on the 'amounts' that he's making.
 
You'd better look more deeply, because it ain't that simple. The overall reaction is actually a sequence of several reactions, most of them binary. That is, two reactants produce a third (product) material. But that third is an intermediate - it becomes the input reactant for the next step in the sequence. And somewhere along the sequence we find that one of the reactions is the slowest of them all. It becomes the "Rate-Determining Step", and the rates of all the other preceeding and following reactions don't matter. It is the rate constant and / or the Activation Energy of this one step you need.

Now, even the Activation Energy alone does not help. You also need the temperature and an equation known to link those two to the rate constant, like Eyring's Equation, and the values for its other (fixed) parameters. Then, having found the rate constant, you look at the rate equation and find that, to get to the actual rate, you need the concentrations of the two input reactants and of the product. These are NOT the same as the inputs of original raw materials, etc - the reaction is in the middle of a sequence!

Ooops! My age is showing. You're trying to get answers fast on the internet, and I'm telling you to check out books!
It comes down to knowing what the original questions were. Were you asked to find the rate constants and Activation Energies (or Enthalpies and Entropies)? Were you asked how long it would take to convert x grams of glycerol to nitroglycerine? Be clear what the questions are. Then try looking BOTH in textbooks on Physical Chemistry and on Organic Chemistry. The Phys guys will talk about reaction kinetics, etc. But the specific reaction you talk about is often considered a simple Organic Chem one. Then look more at Industrial Chem and Engineering - you might find it in a text on chemical plant design.
 
Kinetic data can be pretty hard to find in the literature. Also, you need to be careful that any published data matches the conditions you are interested in. I'd start out checking at NIST, although most of their data are for gas-phase reactions:

NIST (http://www.nist.gov/srd/chemkin.htm) and (http://kinetics.nist.gov/kinetics/index.jsp)

Also, Google Scholar isn't that great, yet, for this type of information. You're probably better off with Scitation (scitation.aip.org) or Scirus (www.scirus.com). Even better, go to your local University research library and use Web of Science (http://www.asu.edu/lib/resources/db/webscience.htm) or Inspec (http://www.asu.edu/lib/resources/db/inspec.htm) or whatever else is available. Note that only ASU students will be able to access the actual databases through these links, although they should be available at other research libraries as well.

You might also find some useful information about Nitroglycerin production in one of the Chemical Engineering Encyclopedias (eg. Ullmann's Encyclopedia of Industrial Chemistry).

Finally, if you know the actual chemical mechanism, you can try to estimate reaction rate data from first-principles using Quantum Chemistry software (Gamess, Gaussian, Jaguar, ADF, etc...) and Kinetic software like KHIMERA (www.kintech.ru). Although, this probably only works for gas-phase reactions at this time (I know there are plans to add some basic liquid chemistry functionality, but it is far from trivial).

If all else fails, assume the reaction kinetics are fast and that the reaction proceeds to thermodynamic equilibrium. HYSYS should be able to do this quite easily. If you don't have thermodynamic data for all of the involved compounds, a little research should turn it up.

Good Luck!

 
You must log in or register to reply here.

TRENDING THREADS

Back
Top