Question

Calculate the volume of CSTR in litre required to achieve 70% conversion. The feed contains 10 molA/litre with feed rate of 3 lit/min and rate constant 0.15 for the reaction -rA = k(CA)^1.5.

(a) 3

(b) 9

(c) 18

(d) 27

I have been asked this question during an online interview.

The doubt is from Design Equations for Flow Reactors in portion Ideal Reactors for a Single Reaction, Conversion and Reactor Sizing of Chemical Reaction Engineering

Answer 1

The correct answer is (d) 27

Easiest explanation: \(\frac{τ}{CA0} = \frac{XA}{-rA} = \frac{XA}{k(CA0(1-XA))^{1.5}} \)  

τ = \(\frac{0.7*10}{0.15(10(1-0.7))^1.5} \)

τ = \(\frac{V}{V0} \) = 8.981 min

V = 8.98*3 = 26.94 lit .