Litmus test in ACIDS AND BASES – Class 7 Science Experiment
Chapter Name: ACIDS AND BASES
Activity Name: Litmus test in ACIDS AND BASES
Activity Description:
In this experiment, we will perform the litmus test on various solutions, including juices of fruits and vegetables, cold drinks, and other solutions, using both blue and red litmus papers. The litmus test is a simple method to identify whether a substance is acidic or basic (alkaline).
Required Items:
- Blue litmus paper
- Red litmus paper
- Solutions of juices from different fruits and vegetables
- Cold drinks
- Various other solutions (to be specified)
Step by Step Procedure:
- Gather all the required items.
- Prepare solutions of juices from different fruits and vegetables.
- Collect some cold drinks and other solutions to test.
- Cut small strips from both blue and red litmus papers.
- Dip the blue litmus paper strip into each solution and observe any color change.
- Record the observations in Table 3 under the column “Effect on Blue Litmus.”
- Rinse and dry the apparatus between tests to avoid contamination.
- Now, dip the red litmus paper strip into each solution and again observe any color change.
- Record the observations in Table 3 under the column “Effect on Red Litmus.”
Experiment Observations:
TABLE 3
| Substance | Effect on Blue Litmus | Effect on Red Litmus |
|---|---|---|
| Juice of Fruit A | Turns red to blue | No change |
| Juice of Fruit B | No change | Turns blue to red |
| Juice of Vegetable A | Turns red to blue | No change |
| Juice of Vegetable B | No change | No change |
| Cold Drink X | No change | Turns blue to red |
| Cold Drink Y | Turns red to blue | No change |
| Solution 1 | No change | No change |
| Solution 2 | Turns red to blue | No change |
Note down your observations in below table format
Precautions:
- Use clean and dry test tubes or containers for each solution to avoid contamination.
- Handle litmus papers with clean and dry hands to get accurate results.
- Rinse the litmus papers between tests to remove any residue from previous tests.
- Make sure to use fresh litmus papers for each test to ensure reliable results.
- Dispose of the used solutions responsibly and follow appropriate waste disposal guidelines.
Lesson Learnt from Experiment:
From the experiment, we observed that substances that turned blue litmus paper to red are acidic, while substances that turned red litmus paper to blue are basic (alkaline).
Substances that did not cause any color change on either blue or red litmus papers are likely neutral in nature. The litmus test is a quick and effective way to determine whether a substance is acidic, basic, or neutral.
