Question

What is the value of F?

(a) 98.5 Kg/hr

(b) 131.1 Kg/hr

(c) 167.7 Kg/hr

(d) 256.4 Kg/hr

This question was addressed to me in a job interview.

The question is from Material Balances Problems Involving Multiple Units in section The Chemical Reaction Equation & Stoichometry, Material Balances for Processes Involving Reaction and Multiple Units of Basic Chemical Engineering

Answer 1

Right answer is (c) 167.7 Kg/hr

The best I can explain: Material balance for ethanol: 200*0.2 = F*0.05 + D*0.98, => 5F + 98D = 4000, material balance for water: 200*0.8 = F*0.95 + D*0.02, => 95F + 2D = 16000, Solving both equations we get F = 167.7 Kg/hr.