Ideal CSTR mass balance for a first order reaction

[@crazygur1y]

thank you, very helpful :)

[@medotedo8410]

so in mass balance there is generation and consumption which part you chose to be the reaction ? I did not get why you added negative then negative and tuned to positive. would you elaborate more on what you said as reaction frequency 1/s

[@LasseGreiner]

Reactions can be treated like transactions in your bank account. As you propose you can split them up to generation and consumption. Alternative the sign of the transaction decides whether it is income or debt. From my teaching experience the formal treatment of this baffles newcomers to the field and is plainly ignored by experienced field engineers. It is connected to the formal treatment of reactions and this tends to be counter intuitive as well. My advice is to put this aside and leave it to the nerds (apparently me) in the field and follow pragmatic approach. For a given system (aA+bB+cC+... -> pP + qQ + rR + ....) it actually quite easy to decide on the sign of the reaction. For the consumed ones this is overall negative (vanishing... not really, but you know what I mean) and for the products it is positive (appearing) if you follow input -output +accumulation +/-reaction = 0 for every species on its own. This is similar to the approach you suggested treating products in "generation" and starting material as "consumption", is it not? Nothing wrong with that as it gets the job done. Hope this is helpful? Maybe I should do a dedicated video on this. Maybe the mass balance example for students resting state ( kzbin.info/www/bejne/p4vamWx4jbV7hqs ) is helpful. Please let me know.

[@medotedo8410]

@@LasseGreinerThank you very much Sir. I am actually a chemical engineering undergraduate and I did finish chemical reactive process course and as you can see I still can not get some concept my Dr. was fired because they discovered that he did fake his degree I was having difficult time understanding the course. He always contradicts thing which make the course horrible to me. I am also wondering why you take accumulating to the other side with positive sign from what I know "Octave Levenspiel - Chemical reaction engineering" always I saw it as - (dN_A)/dt or - (dC_A)/dt because we are writing the balance on reactant A which is consumed. Is that why when you changed the position you gave it positive sign ?

[@medotedo8410]

Sir I will appreciate it if you can help me in understanding why generation is minus here instead of positive: i.ibb.co/7YrBNj7/image.png for me I think it's positive because the concentration that is used is for the A (product) not Ai (reactant) thus there is generation of product + as you can see all information is there to decide correctly. Appreciation.

[@LasseGreiner]

That is why I avoid using "generation". It is reaction and then for starting material undergoing the change it has to be considered negative, whereas for a product it has to be considered positive. This goes along the conventention that in a reaction aA + bB +.... -> pP + qQ +.... reaction rate = (dA/dt) /a = (dB/dt) /b = (dP/dt) /p with the starting material the stoichiometric coefficients (here a and b) are negative and for the products are positive. Then if you put the rate into the mass balance term the sign is given by the coefficient.

[@harithalsamarai119]

Hello, how are you professor, I am an oil refining engineering student and I need to contact you if possible

[@LasseGreiner]

You can find me at Hochschule Mannheim, BioTechnology