A diffusion experiment by itself would just give us an experimental value of the Diffusion Coefficient. If the temperature and particle number density of the solute are known this leaves the molecular mass and cross-sectional radius as unknowns. So we get one curve with two unknowns which is unsolvable. If the molecular mass can be found by some other means such as by using a mass spectrometer then the Diffusion Coefficient will allow us to make an estimate of the molecular cross-sectional radius. This information might help to determine if a molecule was a compact ball or more of a thin rod.
The results of experiments such as these are used to determine the properties of molecules and are useful in identifying the presence of chemical compounds in a mixture. Two analytical tools used in chemistry and biology similar to diffusion are chromatography and electrophoresis.