A 2.00 liter vessel is ?lled with NH3(g) to a pressure of 4.00 atm and the reaction N2(g) + 3 H2(g) ?? 2 NH3(g) comes to equilibrium at a ?xed temperature. At equilibrium it is found that the pressure of H2 is 1.7 atm. What is the equilibrium pressure of NH3? Answer in units of atm.