Practical activity - producing salts
There are a number of ways that you could produce salts in Chemistry. This is an outline of the required steps to undertake one of these methods.
It is important in this practical activity to safely use a Bunsen burner and a water bath. This includes the safe use of a range of equipment to separate and purify mixtures, including filtration and crystallisation.
Aims
To investigate the preparation of A substance that consists of only one element or only one compound., dry hydrated copper sulfate A solid containing particles (atoms, molecules or ions) joined together to form a regular arrangement or repeating pattern. from copper oxide.
Method
The reaction
1. Add some dilute sulfuric acid to a small beaker.
2. Add some hot water from a kettle to larger beaker or water bath. Place the beaker of sulfuric acid into the hot water to warm up the acid.
3. Add a spatula of copper oxide powder to the acid and stir with a glass rod. Continue adding copper oxide powder until it is in In chemistry, a substance is in excess if there is more than enough of it to react with another reactant..
Filtration
4. Fold a piece of filter paper and put it into a filter funnel. Fit the filter funnel into a conical flask.
5. Add the reaction mixture from the beaker to the filter paper.
6. Collect the Fluid that has passed through a filter., the copper sulfate Mixture formed by a solute and a solvent.. Do not collect the The material left over at the end of a process, often the material that is removed during purification of a substance., the unreacted copper oxide.
7. Pour the filtrate into an evaporating basin.
Crystallisation
8. Set up a Bunsen burner, tripod and gauze on a heat resistant mat.
9. Put a beaker of water on the gauze and the evaporating basin on the beaker.
10. Heat the water, adjusting the Bunsen burner flame so the water is just simmering.
11. Stop heating before all the water in the evaporating basin leaves the copper sulfate solution.
12. Allow the evaporating basin to cool, then leave it aside for a few days or in a drying oven.
Results
Record the appearance of the copper sulfate crystals, including their colour and shape.
Analysis
Hydrated copper sulfate crystals should be blue and regularly shaped. Describe how your crystals compare to this description. Suggest an explanation for any differences.
Evaluation
Question
Explain why the sulfuric acid is warmed at step 2.
Warm acid will react faster than cold acid, helping to ensure that all the acid reacts with the copper oxide.
Question
Explain why an excess of the solid reactant is used at step 3.
This makes sure that all the acid has reacted. The process of passing a mixture through a device - soluble substances pass through the filter as a 'filtrate' but insoluble substances or unwanted material will stay in the filter as a 'residue'. then removes the unreacted Unable to dissolve in a particular solvent. For example, sand is insoluble in water.reactant from the salt solution. As the acid is all used up and the insoluble reactant has been removed, this only leaves the salt and water. Therefore, evaporating the water leaves the pure salt.
Question
Describe how you could modify the method to make a pure, dry sample of an insoluble salt.
Mix together two suitable reactants. Use Method used to separate an insoluble solid from a liquid using a physical barrier such as paper. to separate the A suspension of particles in a liquid formed when a dissolved substance reacts to form an insoluble substance, eg in a precipitation reaction. as a residue from the solution. Wash the precipitate while it is in the filter funnel, with distilled water. This works because the precipitate is insoluble.
Hazards, risks and precautions
Evaluate the hazards and the precautions needed to reduce the risk of harm. For example:
| Hazard | Possible harm | Possible precaution |
| Sulfuric acid | Concentrated acid is corrosive and damages skin and clothes | Use dilute sulfuric acid |
| Boiling water bath | Skin burns | Ensure the boiling water bath is stable on the gauze |
| Hot copper sulfate solution spitting out during crystallisation | Damage to eyes and skin | Wear eye protection and avoid standing over the hot apparatus |
| Hazard | Sulfuric acid |
|---|---|
| Possible harm | Concentrated acid is corrosive and damages skin and clothes |
| Possible precaution | Use dilute sulfuric acid |
| Hazard | Boiling water bath |
|---|---|
| Possible harm | Skin burns |
| Possible precaution | Ensure the boiling water bath is stable on the gauze |
| Hazard | Hot copper sulfate solution spitting out during crystallisation |
|---|---|
| Possible harm | Damage to eyes and skin |
| Possible precaution | Wear eye protection and avoid standing over the hot apparatus |