Obtaining Pure Copper Sulphate Solution from an Impure Sample

To obtain pure copper sulphate solution from an impure sample, we can follow the process of purification through crystallization. This process involves dissolving the impure copper sulphate in water, filtering the solution to remove insoluble impurities, and then allowing the solution to cool and crystallize to obtain pure copper sulphate crystals. The detailed steps are as follows:

Materials Required:
- Impure copper sulphate sample
- Water
- Beaker or glass container
- Filter paper or funnel
- Heat source (e.g., Bunsen burner)
- Tripod stand and wire gauze
- Glass rod or stirring rod

Procedure:

1. Dissolving the Impure Copper Sulphate:

- Measure a suitable amount of the impure copper sulphate sample.
- Transfer the sample into a beaker or glass container.
- Add a predetermined amount of water to the beaker, ensuring that the water is sufficient to dissolve the impure copper sulphate completely.
- Stir the mixture with a glass rod or stirring rod until the impure copper sulphate dissolves completely in water.


2. Filtration:

- Set up a filtration apparatus by placing a funnel on top of a filter paper or filter funnel.
- Pour the copper sulphate solution obtained in the previous step into the funnel.
- Allow the solution to pass through the filter paper or filter funnel, collecting the filtrate in a clean container. This step helps remove insoluble impurities present in the impure sample.


3. Crystallization:

- Transfer the filtrate, which contains the dissolved copper sulphate, into an evaporating dish or beaker.
- Place the evaporating dish or beaker on a tripod stand with a wire gauze.
- Heat the solution gently using a Bunsen burner to evaporate the water. Stir the solution continuously to prevent the formation of large crystals.
- Continue heating until the volume of the solution reduces to about half of its original volume or until crystals begin to form on the surface.
- Remove the evaporating dish or beaker from the heat source and allow it to cool slowly. This will promote the formation of large, pure copper sulphate crystals.


4. Collection of Pure Copper Sulphate Crystals:

- Once the solution has cooled, carefully collect the pure copper sulphate crystals formed by using a spatula or any other suitable tool.
- Transfer the crystals into a separate container and allow them to air-dry for a period of time.
- Weigh the dried crystals to determine the yield of pure copper sulphate obtained.

Conclusion:

By following the above procedure, we can obtain pure copper sulphate solution from an impure sample. The process involves dissolving the impure sample in water, filtering to remove insoluble impurities, and then allowing the solution to cool and crystallize to obtain pure copper sulphate crystals. Crystallization is an effective method for purifying substances and obtaining them in their purest form.