Final answer:
To achieve a chloride ion concentration of 0.333 M using 4.21 g of CoCl3, the final volume of the solution should be approximately 0.2286 liters.
Step-by-step explanation:
To determine the final volume of the solution in which [Cl−] is equal to 0.333 M, we first need to calculate the amount of CoCl3 in moles. CoCl3 contains three chloride ions for each formula unit. Therefore, to achieve a chloride concentration of 0.333 M from CoCl3, the concentration of CoCl3 must be 0.111 M because each unit of CoCl3 dissociates into three Cl− ions.
Using the molar mass of CoCl3, which is roughly 165.87 g/mol, we can convert the mass of 4.21 g of CoCl3 to moles:
4.21 g CoCl3 × (1 mol / 165.87 g) = 0.02538 mol CoCl3
Since molarity (M) is defined as moles of solute per liter of solution, the final volume of the solution can be calculated using the molar concentration of CoCl3:
Volume = Moles of solute / Molarity of CoCl3
Volume = 0.02538 mol / 0.111 M = 0.2286 L
Therefore, the chemist must dissolve 4.21 g of CoCl3 in a final volume of approximately 0.2286 liters to achieve a chloride ion concentration of 0.333 M.