At a certain temperature, 0.660 mol of SO3 is placed in a 3.00 L container.

2SO3=>2SO2+O2

Kc=

To find the value of Kc, we need the equilibrium concentrations of SO2 and O2. We can calculate these concentrations based on the given information and use them to find the equilibrium constant.

Step 1: Calculate the initial concentration of SO3:
Number of moles of SO3 = 0.660 mol
Volume of the container = 3.00 L
Initial concentration of SO3 = Moles/Volume = 0.660 mol/3.00 L = 0.220 M

Step 2: Assume that at equilibrium, x moles of SO3 have reacted, and thus, x moles of SO2 and x/2 moles of O2 have been formed.
Using the stoichiometry of the reaction, we can write the equilibrium concentrations as follows:
[SO3] = 0.220 - x M
[SO2] = x M
[O2] = x/2 M

Step 3: Substitute the equilibrium concentrations into the equilibrium expression for Kc:
Kc = ([SO2]^2[O2]) / [SO3]^2
= ([x]^2[(x/2)]) / ([0.220 - x]^2)

Step 4: Simplify the equation if possible:
Kc = (x^3/2) / (0.220 - x)^2

Therefore, the expression for Kc is:
Kc = (x^3/2) / (0.220 - x)^2

To find the value of Kc, we need to use the balanced equation and the given moles and volume of the container.

The balanced equation is:
2SO3 => 2SO2 + O2

Since the coefficient of SO3 is 2, we need to divide the moles by 2:
Moles of SO3 = 0.660 mol / 2 = 0.330 mol

The volume of the container is given as 3.00 L.

Now, we can use these values to calculate the concentration of each species.

Concentration of SO3 = moles/volume = 0.330 mol/3.00 L = 0.110 M

Concentration of SO2 = 0 (since no products have been formed initially)

Concentration of O2 = 0 (since no products have been formed initially)

Finally, we can calculate the value of Kc using the concentrations of the reactants and the products.

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

Kc = (0 * 0) / (0.110^2)

Kc = 0