Posted by L on .
The Kp for the following equilibrium system is 4.31 x 10‒4 at 375°C : N2(g) + 3H2(g) ↔ 2NH3(g).
If 0.862 atm of N2 and 0.373 atm of H2 were mixed in a constantvolume flask and heated to 375°C, which of the following would be closest to the equilibrium partial pressure of NH3 ?
(1) 0.860 atm (2) 4.40 x 10‒3 atm (3) 2.75 x 10‒4 atm (4) 0.366 atm (5) 1.09 x 10‒2 atm

Chemistry 
DrBob222,
..............N2 + 3H2 ==> 2NH3
initial....0.862..0.373......0
change.....p......3p......+2p
equil...0.862p..0.3733p....2p
I looked on the web to find an equation solver for quartics; I'm sure they are there but I didn't find them. I suggest you try substituting the value for NH3 (and the others) into the equation and see which is the closest. That's probably what the author of the problem expected you to do anyway. 
Chemistry 
L,
Thank You!