AP Chem
posted by Bill .
At a particular temperature, Kp = 0.25 for the following reaction.
N2O4(g) 2 NO2(g)
(a) A flask containing only N2O4 at an initial pressure of 5.3 atm is allowed to reach equilibrium. Calculate the equilibrium partial pressures of the gases.
(b) A flask containing only NO2 at an initial pressure of 7.0 atm is allowed to reach equilibrium. Calculate the equilibrium partial pressures of the gases.

You should get into the habit of using an arrow; otherwise we must guess which are products and which are reactants.
..........N2O4 ==> 2NO2
initial....5.3atm....0
change.....p.....2p
equil..... 5.3p....2p
Kp = 0.25 = (NO2O^2/(N2O4)
Substitute from the ICE chart into Kp expression and solve for p.
Then 2p = PNO2 and 5.3p = PN2O4.
For #2,
...........N2O4 ==> 2NO2
initial......0........7
change......+p........p
equil........p.......7p
Substitute into Ka and solve for p.