1. Chemical Formula:

* Calcium chloride has the formula CaCl₂. This means each formula unit of calcium chloride contains two chloride ions (Cl⁻).

2. Molar Ratio:

* For every 1 mole of CaCl₂ dissolved, there are 2 moles of Cl⁻ ions produced.

3. Calculation:

* Since the solution is 2.0 M in CaCl₂, the concentration of chloride ions is twice that:

* [Cl⁻] = 2.0 M CaCl₂ * (2 mol Cl⁻ / 1 mol CaCl₂) = 4.0 M

Therefore, the concentration of chloride ion in a 2.0 M solution of calcium chloride is 4.0 M.