N = PV/RT = 26.3× 0.50/[8.3/kloc-0 /× 318] = 0.00498 mol.
Assume that the amount of NO2 at equilibrium is 2xmol；; The amount of N2O4 is 0.0030-xmol.
The total mass at equilibrium is 0.00498=(0.0030-x+2x).
X = 0.00 198 mol.
The decomposition rate of N2O4 at 45℃ is x/0.0030=0.66.
The standard equilibrium constant k = (2x/0.5) ∧ 2/[(0.0030-x)/0.5] = 0.123.
(2) and (3) We need to check the standard enthalpy change and standard entropy of 25 degrees to get the result.