Posted by Kyo on .
If the initial pressure of NH3(g) is 0.7317 atm, calculate the % of NH3(g) left over after the reaction reaches equilibrium according to the balanced equation. The value of Kp at 500.0 °C is 67100.00. The initial pressure of the reaction products is 0 atm.
2NH3(g) = N2(g)+3H2(g)

Chemistry 
DrBob222,
initial pressure NH3 = 0.7317 atm.
initial pressure H2 = 0 and N2 = 0
At equilibrium
N2 = x
H2 = 3x
NH3 = 0.7317  2x
Kp = 67,100 = pN2*pH2^3/pNH3^2
Substitute into Kp and solve for x, then convert to NH3, H2, N2.
Finally, pNH3 remaining (from above) to percent of original amount present.