Question

Ten grams of plastic beads with a density of 1.2 g/cm^3 are added to 500 mL of an organic solvent with a density of 0.8 g/cm^3. What is the concentration of the plastic beads in mg/L? (This is a curve ball!)

Answer 1

mass of solute = 10 g = 10000 mg

volume of solute = mass / density = 10 / 1.2 = 8.33 mL = 0.00833 L

volume of solvent = 500 mL = 0.5 L

concentration = mass of solute / volume of solution

                       = 10000 / (0.5 + 0.00833)

                       = 19672 mg/L