Ethene (C2H4) undergoes catalytic hydrogenation to form ethane (C2H6) according to the equation:
C2H4(g) + H2(g) ↔ C2H6(g)
If 6.0 moles of ethene and 6.0 moles of hydrogen are introduced into a 2.0 L sealed vessel and allowed to equilibrate at 200ºC, what is the equilibrium concentration of the ethene (C2H4) in the vessel? (Kc = 6.6 x 108 at this temperature)