Question

A reactor is supplied with 5 moles each of CH3OH and O2, and the following reactions occur, CH3OH + 1/2O2 -> CH2O + H2O and then CH2O + 1/2O2 -> CO + H2O, the conversion of methanol is 80% in first reaction, and conversion of CH2O is 50% in second reaction. How many moles of H2O are produced?

(a) 2

(b) 3

(c) 5

(d) 6

I had been asked this question in an internship interview.

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

Answer 1

The correct choice is (d) 6

The best explanation: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of H2O = (0.8*5) + (0.8*5)*0.5 = 6.