Final answer:
To make a 2.00 M solution of Ca(NO₃)2, 41.025 grams of Ca(NO₃)2 must be added to 125 grams of water.
Step-by-step explanation:
To calculate the mass of Ca(NO₃)2 needed, we first need to determine the number of moles of ions required to make a 2.00 M solution. Since Ca(NO₃)2 dissociates into one Ca²⁺ ion and two NO₃⁻ ions, the molar concentration of Ca²⁺ must also be 2.00 M.
The molar mass of Ca(NO₃)2 is 164.10 g/mol. To find the mass of Ca(NO₃)2 needed, we can use the equation:
Mass (g) = Molar concentration (mol/L) × Volume (L) × Molar mass (g/mol)
Given that the volume of water is 125g, we substitute the values and calculate the mass:
Mass (g) = 2.00 mol/L × 0.125 L × 164.10 g/mol = 41.025 g
Therefore, 41.025 grams of Ca(NO₃)2 must be added to 125 grams of water to make a 2.00 M solution.