OBJECTIVES
 Prepare 2000ppm SO_{4}^{2} solution from Na_{2}SO_{4}
 Prepare 2000ppm SO_{4}^{2} solution from CuSO_{4}
 Prepare fixant solution for glutaldehyde film crosslinking
 Crosslink glutaldehyde films
2000ppm SO_{4}^{2} Solutions
In order to prepare a 2000ppm SO_{4}^{2} solution from Na_{2}SO_{4}, the following calculations were completed:
MW Na_{2}SO_{4}: 142.04 g/mol
MW SO_{4}^{2}: 90.06 g/mol
0.001 g SO_{4}^{2} × (1 mol SO_{4}^{2}/90.06 g SO_{4}^{2}) × (1 mol Na_{2}SO_{4}/1 mol SO_{4}^{2}) × (142.04 g Na_{2}SO_{4}/1 mol Na_{2}SO_{4}) = 0.001479 g Na_{2}SO_{4}
Actual mass Na_{2}SO_{4}: 0.00150 g
0.00150 g Na_{2}SO_{4} × (1 mol Na_{2}SO_{4}/142.04 g Na_{2}SO_{4}) × (1 mol SO_{4}^{2}/1 mol Na_{2}SO_{4}) × (96.06 g SO_{4}^{2}/1 mol SO_{4}^{2}) = 0.00101 g SO_{4}^{2}
Actual concentration: (0.00101 g SO_{4}^{2}/0.5 L) × 106 = 2020 ppm SO_{4}^{2}
 Weigh out ~0.00150g Na_{2}SO_{4}
(Actual Na_{2}SO_{4} Mass: 0.00150g)
 Add the Na_{2}SO_{4} solids to a 500mL volumetric flask
 Within the 500mL volumetric flask, add ~500mL of H_{2}O; however, do not exceed the dilution mark
 Next, stir solution until all the solid dissipate into solution
(Repeat procedure above again for CuSO_{4}^{}.5H_{2}O)
MW CuSO_{4}^{.}5H_{2}O: 249.69 g/mol
0.001 g SO_{4}^{2} × (1 mol SO_{4}^{2}/90.06 g SO_{4}^{2}) × (1 mol CuSO_{4}^{.}5H_{2}O/1 mol SO_{4}^{2}) × (249.68 g CuSO_{4}^{.}5H_{2}O/1 mol CuSO_{4}^{.}5H_{2}O) = 0.00256 g CuSO_{4}^{.}5H_{2}O
Actual mass CuSO_{4}^{.}5H_{2}O: 0.00252 g CuSO_{4}^{.}5H_{2}O
0.00252 g CuSO_{4}^{.}5H_{2}O × (1 mol CuSO_{4}^{.}5H_{2}O/249.68 g CuSO_{4}^{.}5H_{2}O) × (1 mol SO_{4}^{2}/1 mol CuSO_{4}^{.}5H_{2}O) × (96.06 g SO_{4}^{2}/1 mol CuSO_{4}^{.}5H_{2}O) = 0.00097 g SO_{4}^{2}
Actual concentration: (0.00097 g SO_{4}^{2}/0.5 L) × 106 = 1939 ppm SO_{4}^{2}
(Actual CuSO_{4}^{}.5H_{2}O Mass: 0.00252g)
Fixant Solution Preparations
 Weigh out ~200g Na_{2}SO_{4}
(Actual Na_{2}SO_{4} Mass: 200.1459g)
 Add the Na_{2}SO_{4} solids to a 1000mL closed cap plastic bottle
 Next, add ~1000mL of H_{2}O to the bottle along with large magnetic stir bar
 Place container with the solution on a stir plate and stir solution for ~20 minutes or until all solids dissipate into solution
 Add 20mL of concentrated H_{2}SO_{4} to solution and continue stirring for ~10 minutes more
Glutaldehyde Crosslinking Preparations
 After allowing the glutaldehyde PVOH films to completely dry in a Teflon dish, remove the film from the dish
 Add prepared fixant solution to a 150mL beaker along with a stir bar and a Buchner funnel top
 Heat the solution to ~70°C on a hot plate and use a thermometer to measure solution temperature at all times
 Place film in fixant solution for ~1 hour while keeping the temperature around 70°C
 Next, prepare a 100mL 1% HCl solution in a 150mL beaker by adding 1mL of concentrated HCl to 100mL of H_{2}O
 Heat 1% HCl solution to ~70°C as well
 Next, remove film from the fixant solution and rinse thoroughly with H_{2}O
 Place a stir bar in the 1% HCl solution and add a new Buchner funnel top to the beaker
 Add rinsed PVOH film to the 1% HCl solution
 Allow film to remain in the 1% HCl solution for ~30 minutes at a constant temperature of 70°C
 Finally, prepare a 0.2M NaHCO_{3} solution by adding ~1.6g of NaHCO_{3} to 100mL of H_{2}O
(Actual Mass NaHCO_{3}: 1.6801g)
 After ~30 minutes, remove the film from the 1% HCl solution to place into the 0.2M NaHCO_{3} solution for ~15 minutes
 Finally, after 15 minutes remove from the NaHCO_{3} solution and rinse with H_{2}O
 Dry the film thoroughly with a paper towel (dabbing gently) and weigh new mass of the PVOH film
Notes
 H_{2}SO_{4} is a highly corrosive substance, care and safety should be taken at all times
 After treatment with varied solutions, the glutaldehyde film mass changed
(New Mass: 0.5126g)
 New glutaldehyde film after treatment appeared to be more flexible and less transparent
