Final answer:
The query covers nonsteady-state diffusion in relation to the second derivative of concentration with respect to position, which is governed by the differential rate law. Details can be explained using the example of second-order reactions where the rate of reaction is proportional to the concentration of the reactant. The net rate of diffusion also depends on the diffusion constant.
Step-by-step explanation:
The student's question deals with nonsteady-state diffusion, which is a concept in physical chemistry. This concerns the rate of concentration change in relation to the second derivative of concentration with respect to position. It specifies that the differential rate law for this kind of situation includes the concentration of just one reactant.
Detailed explanation can be given considering second-order reactions. In these reactions, the rate of disappearance of a reactant A is proportional to the square of its concentration, often written as '-d[A] / dt = k [A]^2' where [A] is the concentration of A and k is the rate constant. This clearly shows the relationship between the rate of reaction and the concentration of the reactant.
Furthermore, the net rate of diffusion is proportional not only to the concentration difference but also to the diffusion constant D. It plays an important role in defining the speed of diffusion which is affected by various factors like temperature and cohesive and adhesive forces.
Learn more about Nonsteady-State Diffusion