Question

In the two-phase aqueous systems, in ordinary situations the bulk phases are not in equilibrium?

(a) True

(b) False

This question was posed to me during an online interview.

I need to ask this question from Convective Mass Transfer topic in section Mass Transfer of Bioprocess Engineering

Answer 1

Right answer is (a) True

Explanation: Normally, it can be assumed that there is negligible resistance to mass transfer at the actual interface, i.e. within distances corresponding to molecular free paths on either side of the phase boundary. This is equivalent to assuming that the phases are in equilibrium at the interface; therefore, CA1i and CA2i are equilibrium concentrations. As a result it is known that there are special situations, such as when there is adsorption of material at the interface, where the assumption is invalid. However, in ordinary situations, the evidence is that equilibrium does exist at the interface between phases. If the bulk liquids were in equilibrium, no net mass transfer would take place.