User:Melissa Novy/Notebook/CHEM-581/2012/09/19

Objectives

• Make 500 mL of 20 ppm SO₄^-2 as Na₂SO₄ in H₂O.
• Make 500 mL of 20 ppm SO₄^-2 as CuSO₄ in H₂O.
  • These two solutions will be used as standards for atomic absorption.
• Make 1 L of PVOH-glutaraldehyde film fixant solution.
• Filter surfactant-modified Na-MTs.

20 ppm SO₄^-2 Solutions

• Calculations:
  • 0.001 g SO₄^-2 in 0.5 L H₂O gives a 2000 ppm SO₄^-2 solution.

  MW Na2SO4: 142.04 g/mol
  MW SO4-2: 90.06 g/mol
  0.001 g SO4-2 × (1 mol SO4-2/90.06 g SO4-2) × (1 mol Na2SO4/1 mol SO4-2) × (142.04 g Na2SO4/1 mol Na2SO4) = 0.001479 g Na2SO4
  Actual mass Na2SO4: 0.00150 g
  0.00150 g Na2SO4 × (1 mol Na2SO4/142.04 g Na2SO4) × (1 mol SO4-2/1 mol Na2SO4) × (96.06 g SO4-2/1 mol SO4-2) = 0.00101 g SO4-2
  Actual concentration: (0.00101 g SO4-2/0.5 L) × 106 = 2020 ppm SO4-2
  (2020 ppm)(V1) = (20 ppm)(0.5 L)
  V1 = 0.00495 L

  MW CuSO4·5H2O: 249.69 g/mol
  0.001 g SO4-2 × (1 mol SO4-2/90.06 g SO4-2) × (1 mol CuSO4·5H2O/1 mol SO4-2) × (249.68 g CuSO4·5H2O/1 mol CuSO4·5H2O) = 0.00256 g CuSO4·5H2O
  Actual mass CuSO4·5H2O: 0.00252 g CuSO4·5H2O
  0.00252 g CuSO4·5H2O × (1 mol CuSO4·5H2O/249.68 g CuSO4·5H2O) × (1 mol SO4-2/1 mol CuSO4·5H2O) × (96.06 g SO4-2/1 mol CuSO4·5H2O) = 0.00097 g SO4-2
  Actual concentration: (0.00097 g SO4-2/0.5 L) × 106 = 1939 ppm SO4-2
  (1939 ppm)(V1) = (20 ppm)(0.5 L)
  V1 = 0.00516 L

• Procedure:
  1. 0.001479 g of Na₂SO₄ was added to a 0.5 L volumetric flask.
  2. The flask was filled to the mark with deionized H₂O to give a 2000 ppm SO₄^-2 solution.
  3. After the actual concentration of this solution was calculated, 4.95 mL of this solution was pipetted into another 0.5 L volumetric flask.
  4. The flask was then filled to the mark with HPLC grade H₂O to give a 20 ppm SO₄^-2 solution.
  5. Steps 1 through 4 were repeated using two more 0.5 L volumetric flasks and with CuSO₄·5H₂O. Please refer to the calculations for details.