In the laboratory you dissolve 24.7 g of chromium(II) sulfate in a volumetric flask and add water to a total volume of 375 mL.

Question

What is the molarity of the solution? ______ M.

What is the concentration of the chromium(II) cation? ______ M.

What is the concentration of the sulfate anion? ______ M.

Answer 1

Chromium(II) sulfate = CrSO₄ Molar mass = 148.1 g/mol

molarity = moles/liter of solution

moles = 24.7 g x 1 mol/148.1 g = 0.167 moles

liters of solution = 375 ml x 1 L/1000 ml = 0.375 L

Molarity = 0.167 moles/0.375 L = 0.445 M

Concentration of Cr²⁺ ion concentration of SO₄^2- ion = 0.445 M because CrSO₄ ==> Cr²⁺ + SO₄^2-