Classifying salts in ACIDS AND BASES – Class 7 Science Experiment

Chapter Name: ACIDS AND BASES

Activity Name: Classifying salts in ACIDS AND BASES

Activity Description:

In this experiment, students will collect various salt substances and prepare their salt solutions. They will then test these salt solutions using blue litmus and red litmus papers to classify the salts as acidic, basic, or neutral. The experiment also aims to understand why our sweat is salty.

Required Items:

1. Various salt substances (provided by the teacher)
2. Water
3. Test tubes or small containers
4. Blue litmus paper
5. Red litmus paper

Step by Step Procedure:

1. Collect different salt substances from the teacher, ensuring they are labeled appropriately.
2. Prepare a separate salt solution for each salt. To do this, take a small amount of each salt and dissolve it in water in individual test tubes or containers. Stir well until the salt is completely dissolved.
3. Take a piece of blue litmus paper and a piece of red litmus paper.
4. Dip the blue litmus paper into each salt solution one by one and observe any changes in color.
5. Similarly, dip the red litmus paper into each salt solution and observe any changes in color.
6. Based on the observations, classify each salt solution as acidic, basic, or neutral.

Experiment Observations:

For the experiment on classifying salts, we tested three different salt solutions: Salt 1 (e.g., HCl), Salt 2 (e.g., NaOH), and Salt 3 (e.g., Na2CO3). When we dipped blue litmus paper into Salt 1 solution, it remained blue, indicating that the solution is not basic. However, when we used red litmus paper, it turned blue, confirming that the solution is acidic.

On the other hand, when we tested Salt 2 solution with blue litmus paper, it turned red, indicating that the solution is basic. The red litmus paper remained red, confirming that it is not acidic. Lastly, when we used both litmus papers with Salt 3 solution, they showed no color change.

The blue litmus paper remained blue, indicating it is not acidic, and the red litmus paper remained red, indicating it is not basic. Based on these observations, we classified Salt 1 as an acidic salt, Salt 2 as a basic salt, and Salt 3 as a neutral salt.

Precautions:

1. Use separate test tubes or containers for each salt solution to avoid contamination.
2. Ensure that the litmus papers are clean and dry before using them.
3. Handle the salt substances with care, as some salts might be harmful or irritating to the skin or eyes.

Lesson Learnt from Experiment:

Through this experiment, students will learn how to classify salts based on their acidic, basic, or neutral properties. They will understand the concept of acidic and basic salts by observing the color changes in litmus papers.

Additionally, the experiment might also prompt discussions about the nature of salts, how they form, and the role of salts in various biological processes, including the reason why our sweat is salty.