Diffusjonskontrollert

Diffusjonskontrollert refers to a process or phenomenon where the rate of a reaction or change is primarily determined by the speed at which molecules or particles diffuse. This means that the movement of reactants to the reaction site or the removal of products from it is the limiting factor, rather than the intrinsic chemical reaction rate itself.

In many chemical and biological systems, diffusion is a fundamental transport mechanism. When reactions occur, for instance, in a solution, the reactants must first encounter each other. If the reaction is very fast, the rate at which they can diffuse together will dictate how quickly the reaction proceeds. Similarly, in solid-state materials or across membranes, diffusion of species can be the bottleneck for processes like material transport, phase transformations, or biological signaling.

Examples of diffusjonskontrollert processes include certain polymerization reactions, the dissolution of solids in liquids, and the transport of ions across cell membranes. In these scenarios, understanding the diffusion coefficients of the involved species and the geometry of the system is crucial for predicting and controlling the overall process rate. Conversely, a process is not diffusjonskontrollert if the chemical reaction itself is slow and limits the overall rate, even if reactants are readily available due to rapid diffusion.