An improved version of the rate equation for molecular diffusion in a dispersed phase



A frequency domain analysis of reversible molecular diffusion in a granule or relatively stagnant drop of fluid reveals that for the larger values of time the rate equation reduces to

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Compared with an earlier time domain result

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the rate predicted is 15/π2 = 1.516 greater and this has been confirmed by results of experiment. An analysis of time constants shows that the dimensionless group relation

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defines mathematically that which is meant by the larger value of time limitation.