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 CH3OH are there in the products?

(a) 1

(b) 2

(c) 3

(d) 4

This question was addressed to me during an interview.

My enquiry 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

Correct option is (a) 1

For explanation I would say: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of CH3OH = 5 – 5*0.8 = 1.