If you change the Pressure to 4 bar at 700 K, how will the equilibrium composition of H2 change (relative to part (a))? Explain your answer.

Question

The “water-gas” shift reaction is catalyzed by an iron oxide/chromium oxide catalyst at 700 K and 2 bar.

H2O + CO ? CO2 +H2

Answer 1

System pressure has no effect on the equilibrium composition of hydrogen according to the equilibrium criterion relationship derived. Since ??v_i =0, the (P^0/P) term becomes 1.

However, if the pressure became high enough that ideal gas behavior cannot be assumed, the fugacity coefficient terms must be accounted for in the equilibrium relationship:



So the equilibrium composition and therefore the mole fraction of hydrogen could be influenced in that sense.