Sciencemadness Discussion Board

Catalyst

Tabun - 17-4-2015 at 06:27

I've already used the search engine,couldn't find anything.I've also used the other one : google.Still,couldn't find anything.Can somebody tell me,how is the amount of catalyst determinated?I didn't hear anything about this even at school and when it comes to reactions in real life school is the last thing I think about(everything is just too "ideal"...I hope you understand what I'm saying).
So...you calculate the amounts needed for the reaction to produce the substance you want,you add some exces(like HNO3 for...many things) and then how you determinate the amount of catalyst needed?
Let's take as example TATP(since I don't want to make this,you can take any other example,I don't mind).
You calculate how much acetone and peroxide you need to make TATP,you put an exces of peroxide to make sure it's going to be the trimer form and how much acid do you need,depending on what acid you will be using?
Hope you understand what I'm saying.Sorry if it's a stupid question,but I never came across any information regarding the catalyst(except that it speeds up the reaction).

Steam - 17-4-2015 at 07:08

Catalysts provide an alternate pathway for a reaction. In the case which you mentioned it depends of the concentration of acid you add. TATP requires H+ ions in solution for the reaction to proceed. You could really add any amount of H+ ions into solution, but just keep in mind that you will have to neutralize the acid after the reaction is complete- Catalysts are no consumed in the reaction. I like to add somewhere between 5%-20% of mol scale I am working on, however this will change based on the innate speed of the reaction as well as the value of the catalyst. I hope that helps!

zed - 17-4-2015 at 10:51

Depends on the reaction, the reaction conditions, and the catalyst.

Such things are determined experimentally. Easiest thing to do is to follow somebody else's lead.

Chemosynthesis - 17-4-2015 at 14:21

You often start with a small percent due to expense and then optimize if necessary.