Final answer:
When the concentration of a substance in chamber A doubles, the diffusion rate of the substance will increase because diffusion is proportional to the concentration gradient.
Step-by-step explanation:
If the concentration of a substance in chamber A doubles, then the diffusion rate of the substance will generally increase. This is because diffusion rate is proportionally related to concentration differences, according to Fick's First Law of Diffusion. As seen in chemical reactions, doubling the concentration of a reactant in a first-order reaction will double the reaction rate, assuming other conditions are held constant. For example, if the concentration of HI is doubled, the reaction rate will increase from k[HI]² to k(2[HI])² = 4k[HI] ², thus quadrupling the reaction rate.
The explanation for this behavior is that more molecules will diffuse from a region of high concentration to a region of lower concentration, accelerating the process. Hence, for a first-order reaction or a simple diffusion process, an increase in concentration leads to an increase in the rate of diffusion.