Question

CH4 is burnt with 100% excess O2 at atmospheric pressure, if CH4 conversion is 100%, what is the pressure at dew point?

(a) 0.2 atm

(b) 0.4 atm

(c) 0.6 atm

(d) 0.8 atm

I got this question in unit test.

My doubt stems from Saturation in division Real Gases: Equations of State, Single Component Two Phase Systems, Saturation & Condensation of Basic Chemical Engineering

Answer 1

Correct choice is (b) 0.4 atm

The best I can explain: CH4 + 2O2 -> CO2 + 2H2O, Basis: 100 moles of CH4, => moles of O2 reacted = 200, => Product contains, moles of CO2 = 100, moles of H2O = 200, moles of O2 = 200. => Fraction of H2O = 0.4, => Pressure at due point = 1*0.4 = 0.4 atm.