Final answer:
To find the zinc ion concentration of a ZnCl₂ solution, you must calculate the number of moles of ZnCl₂ by dividing the given mass by its molar mass, then divide the number of moles by the solution's volume in liters. This provides the molarity, which equals the zinc ion concentration due to ZnCl₂ dissociation.
Step-by-step explanation:
To calculate the zinc ion concentration in mol/L of a ZnCl₂ solution, we first need to know the molar mass of ZnCl₂. Zinc chloride has a molar mass of approximately 136.3 g/mol. With a sample mass of 39.99 g, we can find the number of moles of ZnCl₂ by dividing the mass by the molar mass:
Number of moles of ZnCl₂ = mass (g) / molar mass (g/mol) = 39.99 g / 136.3 g/mol
Once we have the number of moles, we can calculate the molarity by dividing the number of moles by the volume of the solution in liters:
Molarity (M) = moles of solute / volume of solution (L)
The final step is to note that each formula unit of ZnCl₂ dissociates to form one Zn²⁺ ion, thus the concentration of Zn²⁺ ions will be the same as the molarity of the ZnCl₂ solution.