Final answer:
Dissolving 2 moles of MgCl₂ in water results in 2 moles of Mg²⁺ ions and 4 moles of Cl⁻ ions, giving a total of 6 moles of ions.
Step-by-step explanation:
When 2 moles of MgCl₂ are placed into water, they dissociate completely in the solution because MgCl₂ is a strong electrolyte. The dissociation of magnesium chloride can be represented by the following chemical equation:
MgCl₂ (s) → Mg²⁺ (aq) + 2 Cl⁻ (aq)
According to the stoichiometry of the reaction, for each mole of MgCl₂ that dissociates, 1 mole of Mg²⁺ ions and 2 moles of Cl⁻ ions are formed. Therefore, if you start with 2 moles of MgCl₂, you would end up with 2 moles of Mg²⁺ ions and 4 moles of Cl⁻ ions, resulting in a total of 6 moles of ions in solution. The reference information provided about the atomic ratio and the number of atoms is not directly related to the dissociation process in water. Hence, the answer to the question solely depends on the stoichiometry of the dissolution of MgCl₂ in water.