Short Answer 
The dilution of a solution decreases the concentrations of reactants and products, resulting in a drop in Qc below Kc, which causes the reaction to shift towards the left to produce more reactants. After calculating new concentrations, Qc becomes zero, confirming that the reaction will adjust to re-establish equilibrium.
Step 1: Understand the Effect of Dilution
When the solution is diluted by increasing the volume, the concentration of all species will decrease. Specifically, the value of Qc will drop since it is determined by the concentrations of the reactants and products. When diluted, this decrease in Qc will make it less than the equilibrium constant Kc, leading the reaction to shift towards the left to formulate more reactants.
Step 2: Calculate the New Concentrations
To determine the new concentrations following the dilution, follow these steps:
- Calculate the initial concentrations by halving each species since the volume has doubled.
- Next, derive the new concentrations using the new total volume, ensuring water’s concentration is accurately represented.
- For instance, if the initial concentration of Cl2 was represented as x, the new concentration will be x/2.
Step 3: Determine Qc and System Response
After calculating the new concentrations, substitute them into the expression for Qc. Since the concentration of products formed from the reaction is zero initially, Qc will be ( frac{0}{frac{x}{2}} = 0 ). Because Qc is less than Kc (which is ( 4.8 times 10^{-4} )), this indicates that the reaction will shift left to create more reactants, ultimately re-establishing equilibrium in the system.