Answer:
9.2
Explanation:
Let's do an equilibrium chart of this reaction:
2NO(g) + O₂(g) ⇄ 2NO₂(g)
4.9 atm 5.1 atm 0 Initial
-2x -x +2x Reacts (stoichiometry is 2:1:2)
4.9-2x 5.1-x 2x Equilibrium
The mole fraction of NO₂ (y) can be calculated by the Raoult's law, that states that the mole fraction is the partial pressure divided by the total pressure:
y = 2x/(4.9 - 2x + 5.1 -x + 2x)
0.52 = 2x/(10 - x)
2x = 5.2 -0.52x
2.52x = 5.2
x = 2.06 atm
Thus, the partial pressure at equilibrium are:
pNO = 4.9 -2*2.06 = 0.78 atm
pO₂ = 5.1 - 2.06 = 3.04 atm
pNO₂ = 2*2.06 = 4.12 atm
Thus, the pressure equilibrium constant Kp is:
Kp = [(pNO₂)²]/[(pNO)²*(pO₂)]
Kp = [(4.12)²]/[(0.78)²*3.04]
Kp = [16.9744]/[1.849536]
Kp = 9.2
