How many moles of ions are in 27.5 g of MgCl2

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Determine the molar mass of MgCl2. Magnesium (Mg) has an atomic mass of approximately 24.3 g/mol, and Chlorine (Cl) has an atomic mass of approximately 35.5 g/mol. Since there are two chlorine atoms in MgCl2, the molar mass of MgCl2 is calculated as follows: Molar mass of MgCl2 = (24.3 g/mol) + 2(35.5 g/mol).

Calculate the number of moles of MgCl2 in 27.5 g using the formula: Number of moles = mass (g) / molar mass (g/mol).

Recognize that MgCl2 dissociates into Mg^2+ and 2 Cl^- ions in solution. Therefore, for each mole of MgCl2, there are 3 moles of ions (1 mole of Mg^2+ and 2 moles of Cl^-).

Multiply the number of moles of MgCl2 by 3 to find the total number of moles of ions produced when MgCl2 dissociates.

The result from the previous step gives you the total number of moles of ions present in 27.5 g of MgCl2.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). For ionic compounds like magnesium chloride (MgCl2), the molar mass is calculated by summing the atomic masses of all the atoms in the formula. In this case, the molar mass of MgCl2 is approximately 95.21 g/mol, which is essential for converting grams to moles.

Stoichiometry

Stoichiometry is the area of chemistry that deals with the relationships between the quantities of reactants and products in a chemical reaction. In the context of MgCl2, understanding stoichiometry allows us to determine how many moles of ions are produced from a given mass of the compound. Each formula unit of MgCl2 dissociates into one magnesium ion (Mg²⁺) and two chloride ions (Cl⁻), leading to a total of three moles of ions per mole of MgCl2.

Ionic Compounds and Dissociation

Ionic compounds, such as MgCl2, consist of positively and negatively charged ions held together by ionic bonds. When dissolved in water, these compounds dissociate into their constituent ions. For MgCl2, this means that one mole of the compound yields three moles of ions (1 Mg²⁺ and 2 Cl⁻). Understanding this dissociation is crucial for calculating the total number of moles of ions present in a given mass of the compound.