How many moles of chloride ions are there in 2 moles of calcium chloride?

Explanation:

Start by writing the chemical formula of calcium chloride.

The suffix -ide in chloride means that chlorine is working as the ion Cl⁻, this is with oxidation state -1.

Calcium, being an alkaline earth metal, uses oxidation state +2, Ca²⁺

Then, two atoms of Cl are combined with one atom of calcium, because in this way each Cl atom will accept one electron from a Ca atom, which will donate its two valence electrons.

That is indicated in the chemical formula with subscripts: CaCl₂, meaning that each formula-unit of calcium chloride has 2 ions of chlorine and 1 ions of calcium, or twice the number of moles of chloride ion.

       ⇒ 2 mol CaCl₂ : 2 mol Ca⁺ : 4 mol Cl⁻

Hence, there are 4 moles of chloride ions in 2 moles of calcium chloride.