50.0 g N2O4 is introduced into an evacuated 2.00 L vessel at a particular temperature and allowed to come to equilibrium with its decomposition product, NO2. Kc = 0.133 for N2O4(g) <=> 2NO2(g) at this temperature. Once the system has reached equilibrium, 5.00 g of NO2 is injected into the vessel, and the system is allowed to equilibrate once again. Calculate the mass of NO2 in the final equilibrium mixture.
a. 19.7 g
b. 15.5 g
c. 12.4 g
d. 14.7 g
e. 17.8 g