Understanding the Concept

Dilution involves reducing the concentration of a solution by adding more solvent (in this case, water). We can use the following formula:

* M₁V₁ = M₂V₂

Where:

* M₁ = Initial molarity of the solution

* V₁ = Initial volume of the solution

* M₂ = Final molarity of the solution

* V₂ = Final volume of the solution

Solving the Problem

1. Identify the known values:

* M₁ = 1.000 M (initial molarity)

* V₁ = 100 mL (initial volume)

* M₂ = 0.31 M (final molarity)

2. Solve for V₂ (final volume):

* V₂ = (M₁V₁) / M₂

* V₂ = (1.000 M * 100 mL) / 0.31 M

* V₂ ≈ 322.58 mL

3. Calculate the volume of water added:

* Volume of water added = V₂ - V₁

* Volume of water added ≈ 322.58 mL - 100 mL

* Volume of water added ≈ 222.58 mL

Answer: Approximately 222.58 mL of water would need to be added to the 100 mL of 1.000 M sodium chloride solution to obtain a 0.31 M solution.