There's no evidence to suggest that potassium ferrocyanide and ferric chloride diffuse at the same rate. In fact, they likely diffuse at different rates.

Here's why:

* Molecular size and weight: Potassium ferrocyanide ([K₄Fe(CN)₆]) is a much larger molecule than ferric chloride (FeCl₃). The size and weight of molecules significantly impact their diffusion rates. Larger molecules tend to diffuse slower than smaller ones.

* Ionic charges: Potassium ferrocyanide and ferric chloride are ionic compounds. While both dissolve in water, they dissociate into different ions:

* Potassium ferrocyanide: K⁺ and Fe(CN)₆⁴⁻

* Ferric chloride: Fe³⁺ and Cl⁻

* These ions have different charges, which affect their interactions with water molecules and, therefore, their diffusion rates.

* Solvent conditions: The diffusion rate is also influenced by the properties of the solvent. For example, the viscosity and temperature of the solvent play a role.

In summary: There is no reason to expect potassium ferrocyanide and ferric chloride to diffuse at the same rate. Their size, charge, and the properties of the solvent all contribute to different diffusion rates.

To determine the actual diffusion rates, you would need to conduct experiments measuring the diffusion coefficients of each compound under specific conditions.