at a certain temperature 800 mole of so3 is placed in a 4.00-l container.

2SO3(g)<-->2SO2(g)+O2(g)

at equilibrium, 0.120 mol of o2 is present.

calculate kc

**.800 mol of so3

To calculate the equilibrium constant (Kc) for the given reaction, we need to know the concentrations of the reactants and products at equilibrium. In this case, we are given the initial number of moles of SO3 (800 mol) and the number of moles of O2 at equilibrium (0.120 mol).

First, we need to convert the moles of O2 to its concentration in mol/L. The volume of the container is given as 4.00 L.

Concentration of O2 (cO2) = number of moles of O2 / volume of the container
cO2 = 0.120 mol / 4.00 L

Now, we can write the expression for the equilibrium constant (Kc) using the concentrations:

Kc = [SO2]^2 * [O2] / [SO3]^2

Since the stoichiometric coefficient for O2 is 1 in both the reactant and product side, we don't need to square its concentration. However, we need to square the concentrations of SO2 and SO3 because their coefficients are 2 in the balanced equation.

Assuming the initial concentration of SO3 is 800 mol / 4.00 L = 200 mol/L (since there are 800 moles in a 4.00 L container), the equilibrium constant can be calculated as follows:

Kc = ([SO2] * [O2]) / [SO3]^2
= ([SO2] * (0.120 mol / 4.00 L)) / (200 mol/L)^2

Now, you can substitute the appropriate values and calculate the equilibrium constant (Kc).