One mole of N2 and 3 moles of H2 are placed in a flask at 375 degree celsius.?

Question

Calculate the total pressure of the system at equilibrium if the mole fraction of NH3 is found to be 0.21. The Kp for the reaction is 4.21 x 10 raise to -4

Answer 1

......N2 + 3H ==> 2NH3
I.....1.....3.......0
C....-x...-3x......2x
E....1-x..3-3x.....2x

Ptotal = 1-x+3-3x+2x = 4-2x
Then XNH3 = (2x/4-2x)= 0.21
Solve for x, then evaluate pNH3, pN2 and pH2. Finally, Ptotal = the sum of the partial pressures.