At a particular temperature, 12.6 mol of SO3 is placed into a 4.0-L rigid container, and the SO3 dissociates by the reaction given below. 2 SO3 (g) equilibrium reaction arrow 2 SO2 (g) + O2 (g) At equilibrium, 3.4 mol of SO2 is present. Calculate K for this reaction.

At equilibrium, Kc = 0.058

Explanation:

Step 1: Data given

Mol SO3 = 12.6

Volume = 4.0 L

At equilibrium we have:

3.4 mol of SO2

Step 2: The balanced equation

2SO3 (g) + ⇆ 2SO2 (g) + O2 (g)

Step 3: ICE-chart

The initial number of moles are:

SO3: 12.6 moles

SO2 : 0 mol

O2: 0 mol

There will react:

SO3: - 2x

SO2: + 2x

O2: + x

The number of moles at the equilibrium are:

SO3: 12.6 - 2x

SO2: 2x = 3.4 mol

O2: x

Since at the equilibrium, we have 2x = 3.4 mol. x = 1.7 mol

This means at the equilibrium we have 1.7 mol of O2 and 12.6 - 3.4 = 9.2 mol of SO3

Step 4: Calculate the equilibrium constant Kc

Kc = [3.4/4]² * [1.7/4] / [9.2/4]²

Kc = 0.058

At equilibrium, Kc = 0.058