Question

The effective diffusivity of substrate in the solid, \(\mathcal{D}_{Ac}\) is dependent of substrate.

(a) True

(b) False

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This interesting question is from Internal Mass Transfer and Reaction topic in portion Heterogenous Reactions of Bioprocess Engineering

Answer 1

The correct choice is (b) False

To elaborate: The value of \(\mathcal{D}_{Ac}\) is a complex function of the molecular – diffusion characteristics of the substrate, the tortuousness of the diffusion path within the solid, and the fraction of the particle volume available for diffusion. \(\mathcal{D}_{Ac}\) is constant and independent of substrate concentration in the particle; this means that \(\mathcal{D}_{Ac}\) does not change with position.