Question

For a macrofluid, the average concentration of reactant in the exit stream is _______

(a) \(\frac{\overline{C_A}}{C_{A0}}\) = \(\int_0^∞ \frac{C_A}{C_{A0}}\)dt

(b) \(\frac{\overline{C_A}}{C_{A0}}\) = E.dt

(c) \(\frac{\overline{C_A}}{C_{A0}}\) = \(\int_0^∞\)E.dt

(d) \(\frac{\overline{C_A}}{C_{A0}}\) = \(\int_0^∞ \frac{C_A}{C_{A0}}\)E.dt

The question was posed to me during an interview.

This key question is from Fluid-Fluid Reactions in chapter Fluid-Fluid Reactions: Kinetics & Basics of Non Ideal Flow of Chemical Reaction Engineering

Answer 1

Right answer is (d) \(\frac{\overline{C_A}}{C_{A0}}\) = \(\int_0^∞ \frac{C_A}{C_{A0}}\)E.dt

To elaborate: The average concentration of reactant in the exit stream is the summation of the products of reactant concentration remaining between t and t+dt and the fraction that exits between t and t+dt. The fraction exiting between t and t+dt is given as Edt.