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

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## 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.