To make a copper standard solution, you'll dissolve cupric sulfate in hydrochloric acid and then dilute to the desired concentration. Here's a step-by-step guide:
Materials Needed:
- Cupric sulfate (CuSO₄)
- 0.1 M Hydrochloric acid (HCl)
- Analytical balance
- 1000 ml volumetric flask (x2)
- Pipette (3 ml)
- Distilled or deionized water
Procedure:
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Preparation of the Stock Solution:
- Accurately weigh 1.965 g of cupric sulfate (CuSO₄) using an analytical balance. Record the exact weight.
- Transfer the weighed cupric sulfate to a 1000 ml volumetric flask.
- Add sufficient 0.1 M hydrochloric acid (HCl) to dissolve the cupric sulfate and then fill the flask to the 1000.0 ml mark with 0.1 M HCl.
- Mix thoroughly to ensure the cupric sulfate is completely dissolved and the solution is homogeneous. This is your copper stock solution.
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Preparation of the Working Standard Solution:
- Using a pipette, transfer 3.0 ml of the copper stock solution to a separate 1000 ml volumetric flask.
- Dilute to the 1000 ml mark with 0.1 M hydrochloric acid (HCl).
- Mix thoroughly to ensure the solution is homogeneous. This is your working copper standard solution.
Important Considerations:
- Accuracy: Accurate weighing is crucial for preparing precise standard solutions. Use a calibrated analytical balance.
- Reagents: Use high-quality cupric sulfate and hydrochloric acid.
- Volumetric Flasks: Ensure volumetric flasks are clean and properly calibrated.
- Mixing: Thorough mixing is essential after each addition of solvent to ensure homogeneity.
- Storage: Store the copper standard solution in a clean, airtight container in a cool, dark place to prevent degradation.
- Safety: Wear appropriate personal protective equipment (PPE) when handling chemicals.
This process provides a copper standard solution for analytical purposes. The final concentration will depend on the purity of the cupric sulfate used and the accuracy of your measurements.
