At a certain temperature, 0.920 mol SO3 is placed in a 4.50 L container. 2SO3(g)↽−−⇀2SO2(g)+O2(g) At equilibrium, 0.190 mol O2 is present. Calculate 𝐾c. 𝐾c=

Answer 1

Use an ICE table

2SO₃(g) <==> 2SO₂(g) + O₂(g)

0.920...............0................0..............Initial

-2x.................+2x..............+x............Change

0.920-2x.........2x.................x............Equilibrium

@Equilibrium, x = 0.190 mol (O₂). Thus, we can now find the concentrations of all species @ equilibrium:

[SO₃] = 0.920 - 2(0.190) = 0.920 - 0.380 = 0.54 mols / 4.50 L = 0.120 M

[SO₂] = 2x = 2*0.190 = 0.380 mols / 4.50 L = 0.0844 M

[O₂] = x = 0.190 mol / 4.50 L = 0.0422 M

Next, we simply plug these values into the Keq expression and solve:

Keq = [SO₂]²[O₂] / [SO₃]²

Keq = (0.0844)²(0.0422) / (0.120)²

Keq = 0.0209