Answer is: the molarity of the solution is 0.176 M.
m(MgCl₂) = 8.36 g; mass of magnesium chloride.
M(MgCl₂) = 95.21 g/mol; molar mass of magnesium chloride.
n(MgCl₂) = m(MgCl₂) ÷ M(MgCl₂).
n(MgCl₂) = 8.36 g ÷ 95.21 g/mol.
n(MgCl₂) = 0.0878 mol; amount of magnesium chloride.
V = 500 mL ÷ 1000 mL/L.
V = 0.5 L; volume of the solution.
c(MgCl₂) = n(MgCl₂) ÷ V.
c(MgCl₂) = 0.0878 mol ÷ 0.5 L.
c(MgCl₂) = 0.176 mol/L; the molarity of the solution.