Solution:

Given data:

- Volume of MgCl2 solution = 100 mL
- Number of Cl- ions in solution = 3.01*10²⁰

Molarity of MgCl2 solution can be calculated using the formula:

Molarity = Number of moles of solute / Volume of solution in liters

To calculate the number of moles of MgCl2 in the solution, we need to first calculate the number of moles of Cl- ions in solution.

Calculation of moles of Cl- ions:

- Mass of 1 mole of Cl- ion = Atomic mass of Cl- = 35.5 g/mol
- Number of Cl- ions in 3.01*10²⁰ = 3.01*10²⁰ / Avogadro's number = 3.01*10²⁰ / 6.022*10²³ = 0.050 mol

Calculation of molarity:

- Volume of solution in liters = 100 mL / 1000 mL/L = 0.1 L
- Molarity = 0.050 mol / 0.1 L = 0.5 M

Therefore, the molarity of the MgCl2 solution is 0.5 M.

Explanation:

Molarity is a measure of the concentration of a solution and is defined as the number of moles of solute per liter of solution. In this problem, we are given the number of Cl- ions in the solution and asked to calculate the molarity of the MgCl2 solution.

To do this, we first need to calculate the number of moles of Cl- ions using the atomic mass of Cl-. We can then use this value to calculate the number of moles of MgCl2 in the solution using the stoichiometry of the compound.

Finally, we can use the formula for molarity to calculate the concentration of the solution in terms of moles per liter.

0.4939×10‐³