# What is the equation that describes the variation in concentration of an inhibitor in an heterogeneous catalysis?

I find myself in quite a pinch: I have to sustain a Chemical Physics exam, and I know for a fact that the professor often asks this particular question:

Suppose that we have both a reacting species and an inhibitor in a homogeneous solution, and we insert a solid catalyst in it. What is the equation that describes the variation of the inhibitor's concentration in this heterogeneous catalysis?

I know for a fact that four different types of flows are included (or at least the professor explained it that way): two "scalar" flows, identified by the consumption of reagent and the consumption of inhibitor, and two "vectorial" flows, identified by the creation of a gradient in concentration of the two species.

However, I can't seem to find or even build up a satisfying equation that describes it. Can someone help?

• Maybe you mean Fick's laws? – Buck Thorn Jul 3 at 20:30
• Yes, that's for sure a component of the full equation, but my professor also stated that there's the change in the Michaelis-Menten equation with the (alpha) term in it. So I thought that I had to combine both the M-M and Fick, but I find myself a little lost on how to do so. Can you help me, please? – Claudio Lancia Jul 3 at 20:36
• I suggest you write a set of reaction equations to guide the readers as to what the process in question is. How is the inhibitor involved, why should its concentration change (the free concentration?)... – Buck Thorn Jul 4 at 7:20