Nitrogen dioxide NO2 is one of a number of oxides of nitrogen found in our atmosphere. It

can dimerize to give N2O4 (g):

2NO2 (g)

N 2 O 4 (g)

At 298 K, the ∆G of formation for N2O4 (g) is 98.28 kJ, whereas for NO2 (g) is 51.84

kJ. Starting with one mole of N2O4 (g) at 1.0 atm and 298 K, calculate what fraction

will be decomposed if the total pressure is kept constant at 1.0 atm and the

temperature is maintained at 298 K.

Supposedly the answer is 0.166, but I haven't been able to find the way to solve it correctly, my result was 0.39.

I calculated the constant K with ΔG= -RTlnK. The ΔG for the whole reaction is (according to me) 5.4kJ

The constant I calculated is 0.99782. Then:

(NO

_{2})

^{2}/(N

_{2}O

_{4})

(2x)

^{2}/(1-x)= K

Solve the cuadratic ecuation and it's 0.39, Where did I go wrong?