How many grams of MgF2 will dissolve in 150. mL of 0.100 M NaF solution?
Ksp for MgF2 = 6.4 x 10-9
To determine how many grams of MgF2 will dissolve in 150 mL of 0.100 M NaF solution, we need to calculate the solubility of MgF2 using the Ksp (solubility product constant) value.
Here's how you can calculate it step by step:
Step 1: Write the balanced chemical equation for the dissociation of MgF2.
MgF2 ⇌ Mg2+ + 2F-
Step 2: Write the expression for the solubility product constant (Ksp) using the concentrations of the ions.
Ksp = [Mg2+][F-]^2
Step 3: Convert the volume of the NaF solution to liters.
150 mL = 0.150 L
Step 4: Calculate the concentration of F- in the NaF solution.
Concentration of F- = 0.100 M
Step 5: Use the stoichiometry of the balanced equation to determine the concentration of Mg2+.
Since the ratio of F- to Mg2+ is 2:1, the concentration of Mg2+ is half the concentration of F-.
Concentration of Mg2+ = 0.100 M / 2 = 0.050 M
Step 6: Substitute the concentrations of Mg2+ and F- into the Ksp expression.
Ksp = (0.050)(0.100)^2 = 5.00 x 10^-4
Step 7: Solve for the solubility of MgF2 by rearranging the Ksp expression.
Solubility of MgF2 = √(Ksp)
Solubility of MgF2 = √(5.00 x 10^-4) = 0.022 M
Step 8: Convert the solubility to grams of MgF2 using molar mass.
Molar mass of MgF2 = 62.31 g/mol
Mass of MgF2 = solubility (in moles) x molar mass
Mass of MgF2 = 0.022 M x 0.150 L x 62.31 g/mol = 0.210 g
Therefore, approximately 0.210 grams of MgF2 will dissolve in 150 mL of 0.100 M NaF solution.