For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG: mass transfer co-efficient, moles/m2, a: interfacial area per unit volume of tower) ?

Correct answer: A. G/(FG . a)

A. G/(FG . a)
B. FG/(G . a)
C. (G . a)/FG
D. L/(FG . G)

Explanation

The gas-phase height of a transfer unit is H_G = G/(F_G a), obtained by dividing the gas molar velocity by the volumetric gas-side transfer conductance. Hence option a has the correct units and form.

Written and checked by Zahid Hussain, MS Computer ScienceLast updated 18 September 2026

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For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG: mass transfer co-efficient, moles/m2, a: interfacial area per unit volume of tower) ?

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