I have read many research articles addressing the effect of homogeneous–heterogeneous reaction on fluid flow; all of them mentioned A and B as chemical species. Can anyone help me to understand what A and B are?
For example, consider the isothermal homogenous (cubic) autocatalytic reaction
A+2B ->3B
And first order isothermal heterogeneous reaction
A->B
I have attached a research article with this question.
Thank You!
The symbols A & B (and C,D,...) are abstract designations for chemical species, in the same way that the variables 'x' and 'y' are often used in mathematics textbooks.
Leander Boer, Thank you for your response.
Sir, my concern is to know what kind of chemical species they are taking, are they related to the surface material or something else.
It would be helpful if you could suggest some references on this topic, which will help me to understand this.
Hi Himanshu and all.
The hyphened association of the terms homogeneous and heterogeneous makes the statement rather foggy. What exactly is the reacting system you are dealing with?
Is it a homogeneous reaction followed by a heterogeneous reaction (series reaction)? Or, may be, there are two simultaneous reactions, one homogeneous and another heterogeneous (parallel reactions)? Could it be that the hyphen means simply “or”, that is, only one reaction is taking place (either homogeneous or heterogeneous). Or, even, any of the three previous cases are possible?
Regarding the meaning of A and B, it should be clear from the research article itself what they represent. May be the authors are referring A and B from another research article cited previously by them. There are too many possibilities here. For instance, A could be a reactant specie diffusing towards a catalyst surface and B is the diffusing medium/solvent. Or, could be that A is a reactant and B the product etc. etc.
Thank you for your response, Dr. R. P. Peçanha.
Sir, I am working on the simultaneous effect of homogenous and heterogeneous reactions on fluid flowing over a stretching surface. I want to understand what they meant by species (are they talking about medium and surface particles or the nanoparticles dispersed in base fluid). Further, I have seen many research articles related to this, but most of them have considered only the case where diffusion coefficient of both the species (say E and F) are equal. Thus, they reduced the problem to a homogenous medium. And, I could not understand the purpose of this, is it because it reduces the complexity of the problem or something else.
Sir, it will be helpful if you could suggest some literature related.
Hi Himanshu and all.
In the present context, the term “species” is simply a short form for “chemical species”. That is, a molecule, an ion (cation or anion) or a free radical, either in solution or in a crystal or amorphous phase. Under a variety of circumstances (for instance, a concentration gradient of a given chemical species in a given medium/solvent) they might diffuse and/or react chemically with another chemical species present. So, the very nature of the chemical species present in a given system, together with the prevailing temperature and pressure, determines what might happen or not in that system. In short, when dealing with chemical species you must be very specific about them. In other words, there is no such a thing as a General Theory of Chemical Reactions which would include all known chemical species and multiphase systems. Thus, may be the A and B that are troubling you is just a very very very particular and idealized binary system with two chemical species: A and B. However, even in this case, depending on the chemical nature of A and B phenomena/chemical reactions could differ a lot.
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