Understanding the Formula

* MgCl₂ represents magnesium chloride.

* The subscript "2" after Cl means there are two chloride ions (Cl⁻) for every one magnesium ion (Mg²⁺).

Calculation

1. Moles of chloride ions: Since there are 2 moles of MgCl₂ and each mole of MgCl₂ contains 2 moles of chloride ions, we have:

2 moles MgCl₂ × 2 moles Cl⁻/mole MgCl₂ = 4 moles Cl⁻

2. Number of chloride ions: To find the number of chloride ions, we use Avogadro's number (6.022 x 10²³ particles per mole):

4 moles Cl⁻ × 6.022 x 10²³ ions/mole = 2.409 x 10²⁴ chloride ions

Answer: There are approximately 2.409 x 10²⁴ chloride ions in a sample of salt containing 2 moles of MgCl₂.