Question

The unit of mass transfer coefficient is ______________

(a) m^-1s

(b) ms^-1

(c) m^-1s^2

(d) m^2s^-1

I got this question in exam.

The query is from Convective Mass Transfer in chapter Mass Transfer of Bioprocess Engineering

Answer 1

Correct answer is (b) ms^-1

Explanation: (mol/s)/(m^2•mol/m^3) = m/s

Note, the units will vary based upon which units the driving force is expressed in. The driving force shown here as ‘ΔcA’ is expressed in units of moles per unit of volume, but in some cases the driving force is represented by other measures of concentration with different units. For example, the driving force may be partial pressures when dealing with mass transfer in a gas phase and thus use units of pressure.