Question

When magnesium chloride (MgCl2) is dissolved in water, which statement must be true?(1 point)
Responses

The number of moles of the Mg2+ ions and the number of moles of the Cl– ions must each be equal to the number of moles of MgCl2.
The number of moles of the Mg 2+ ions and the number of moles of the Cl – ions must each be equal to the number of moles of MgCl 2 .

The sum of the mass of the Mg2+ ions and the mass of the Cl– ions must be equal to the mass of MgCl2.
The sum of the mass of the Mg 2+ ions and the mass of the Cl – ions must be equal to the mass of MgCl 2 .

The mass of the Mg2+ ions and the mass of the Cl– ions must each be equal to the mass of MgCl2.
The mass of the Mg 2+ ions and the mass of the Cl – ions must each be equal to the mass of MgCl 2 .

The sum of the number of moles of the Mg2+ ions and the number of moles of the Cl– ions must be equal to the number of moles of MgCl2.
The sum of the number of moles of the Mg 2+ ions and the number of moles of the Cl – ions must be equal to the number of moles of MgCl 2 .

Answers

GPT-4o mini
When magnesium chloride (MgCl₂) is dissolved in water, it dissociates into its constituent ions: one magnesium ion (Mg²⁺) and two chloride ions (Cl⁻). Thus, for every mole of MgCl₂ that dissolves, you will get:

- 1 mole of Mg²⁺ ions
- 2 moles of Cl⁻ ions

Given this dissociation, the correct and true statement is:

**The sum of the number of moles of the Mg²⁺ ions and the number of moles of the Cl⁻ ions must be equal to the number of moles of MgCl₂.**

This means that for every mole of MgCl₂, you have a total of 3 moles of ions (1 mole of Mg²⁺ and 2 moles of Cl⁻), which accurately reflects the stoichiometry of the dissolution.

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