A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (keff) is given by________________?
Correct answer: B. 1/keff = 1/k + 1/kg
- A. keff = k + kg
- B. 1/keff = 1/k + 1/kg
- C. keff = (kkg)1/2
- D. keff = (k+ kg)/2
Explanation
External mass transfer and surface reaction act as consecutive resistances, so their reciprocal effective rate constants add: 1/k_eff = 1/k_g + 1/k. This is analogous to adding resistances in series.
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