Lesson
Purpose of the work:
- To consolidate theoretical knowledge about the chemical properties of salts
Expected results:
After completing the work, students can:
- develop teamwork skills
- be able to analyze and summarize the information received
- draw logical conclusions
Teacher’s Guide:
- The task is performed in groups of 3-4 people
- Before starting laboratory work, please read the safety rules by following the link:
- To download the worksheet, follow the link:
Theoretical part
Structure and properties of salts
- Structure: Salts are complex substances consisting of metal cations and acid residue anions. For example, in table salt (NaCl), the cation is sodium (Na+), and the anion is chloride (Cl-).
- Properties: The properties of salts are very diverse and depend on their composition. They can be solid, liquid, or gaseous, soluble or insoluble in water. Some salts have a bright color, others are colorless.
Chemical properties of salts.
Salts enter into various chemical reactions:
- Exchange reactions: When salts interact with other salts, acids, or bases, ion exchange occurs. For example, when mixing solutions of barium chloride and sodium sulfate, insoluble barium sulfate is formed.
- Interaction with metals: More active metals can displace less active ones from their salts. For example, iron displaces copper from a copper sulfate solution.
- Decomposition upon heating: Some salts decompose upon heating to form other substances. For example, calcium carbonate decomposes when calcined into calcium oxide and carbon dioxide.
Practical application of salts.
Salts are widely used in various fields of human activity:
- Food industry: Table salt, baking soda, sodium nitrite are just a few examples of salts used in the food industry.
- Medicine: Many drugs are salts of various acids.
- Agriculture: Mineral fertilizers contain nitrogen, phosphorus, and potassium salts, which are necessary for plant nutrition.
- Industry: Salts are used in the production of glass, paper, dyes, explosives, and many other products.
Interesting facts about salts
- Sea salt: Sea salt contains many different salts that give it a unique taste and aroma.
- Salt as a preserving agent: Salt is used to preserve food as it prevents the growth of bacteria.
- Salt in nature: Salts play an important role in geological processes such as the formation of caves and salt deposits.
Practical part
Experiment 1. Interaction of salts with bases
Step 1. Pour 2 ml of iron (II) chloride and copper (II) sulfate solutions into two clean test tubes.
Step 2. Add a sodium hydroxide solution to each test tube.
Step 3. Observe the color change of the solutions and the formation of precipitates.
Experiment 2. Interaction of salts with metals
Step 4. Pour 2 ml of copper (II) sulfate solution into two clean test tubes.
Step 5. Place an iron nail in one test tube and a piece of aluminum foil in the other.
Step 6. Observe the color change of the solutions and the appearance of a metallic precipitate.
Experiment 3. Interaction of salts with silver nitrate
Step 7. Pour 2 ml of iron (III) chloride solution into one test tube and the same amount of copper sulfate in the other.
Step 8. Add several drops of silver nitrate solution into each tube.
Step 9. Observe the changes.
Step 10. After a while, observe the results again. In your Worksheets, write the balanced equations of each chemical reaction. Make conclusions about the work.
Conclusion
In this laboratory work, the theoretical knowledge about the chemical properties of salts was confirmed. Exchange reactions, displacement of metals from salts, and precipitation reactions were carried out. Based on the obtained results, it can be concluded that the properties of salts are determined by their composition and structure.