Diffusion equation variational interpretation

The kinetics and mechanism of the oxidation of [Fe(phen)2(CN)2] by HNO have been reported. At low acidities ( 0.1M) in H2SO4, the rate equation is of the form Rate= [H+][HN02]IFe ]2, and the reaction proceeds via diffusion-controlled oxidation of the complex by NO. Under more concentrated conditions ([H2S04] 6M) protonation of the iron(ii) species to yield [Fe(phen)2-(CNH)2] is invoked in the interpretation of the rate variations. 

The most striking change is in the A-term that accounts for multipath dispersion (Equation [3.33] in the van Deemter theory) and decreases rapidly with decreasing i.d. This effect was interpreted (Karlsson 1988) as reflecting a decrease in the extent of the flow rate variation over the column cross-section as the i.d. decreases, together with shorter time for solute molecules to diffuse radially through the flow velocity profile (parabolic in the case of a nonpacked column) together these phenomena will decrease the effect of flow anisotropy that is reflected in... 

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