At a given temperature, the equilibrium constant K for the reaction 2SO2(g) + O2(g) 2SO3(g) is 3.0 × 109. If 2.80 mol of SO2 and 4.06 mol of O2 are placed in a 1.78-L container and allowed to react to equilibrium at this temperature, what is the concentration of SO3 at equilibrium?