The internal effectiveness factor times the square of this quantity gives the Weisz-Prater parameter, which is very small when pore diffusion is negligible. For 10 points each:
[10h] Name this quantity, the coefficient of the concentration term in a differential equation that describes a material balance over a spherical pellet.
ANSWER: Thiele modulus
[10e] The Thiele modulus quantifies the effects of diffusion and particle size in these substances, which reduce the activation energy.
ANSWER: catalysts
[10m] For a reaction limited by external diffusion, the reaction rate does not obey Arrhenius kinetics, instead varying with temperature raised to this power. A uni·molecular rate law in which concentration is raised to this power produces a rate constant with units of inverse seconds.
ANSWER: 1 or one [or first power or unity]
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