For the chemical equation

SO

2

(g)+NO

2

(g)↽−

−⇀

SO

3

(g)+NO(g)

SO2(g)+NO2(g)↽−−⇀SO3(g)+NO(g)

the equilibrium constant at a certain temperature is 3.90.

3.90. At this temperature, calculate the number of moles of NO

2

(g)

NO2(g) that must be added to 2.88 mol SO

2

(g)

2.88 mol SO2(g) in order to form 1.20 mol SO

3

(g)

1.20 mol SO3(g) at equilibrium.