Advertisements
Advertisements
Question
Prepare red cabbage juice by boiling a piece of red cabbage in water. Use it as an indicator and test the acidic and basic solutions with it. Present your observations in the form of a table.
Solution
Red Cabbage Juice as an Indicator:
-
Prepare the Indicator:
- Boil a piece of red cabbage in water until the water turns dark purple. This cabbage juice will act as a pH indicator.
-
Testing Solutions:
- Collect various acidic and basic solutions for testing (e.g., lemon juice, vinegar, baking soda solution, soap water).
-
Observations:
| Solution | Colour Change with Red Cabbage Juice | Nature |
| Lemon Juice | Pink/Red | Acidic |
| Vinegar | Pink/Red | Acidic |
| Baking Soda Solution | Green/Blue | Basic |
| Soap Water | Green/Blue | Basic |
| Distilled Water | Purple (No change) | Neutral |
Explanation:
- Acidic solutions turn the red cabbage juice pink/red.
- Basic solutions turn the red cabbage juice green/blue.
- Neutral solutions show no significant colour change, remaining purple.
RELATED QUESTIONS
Sodium hydroxide turns blue litmus red.
Fill in the following blank with suitable words:
Acids have a pH...........than 7.
The pH values of six solutions A to F are given below:
A = 0, B = 11, C = 6, D = 3, E = 13, F = 8
Which of the above solutions are (i) acids (ii) alkalis?
The pH values of five solutions A, B, C, D and E are given below:
| A | 1 |
| B | 5 |
| C | 7 |
| D | 11 |
| E | 13 |
Which solution is weakly alkaline.
Solution A turns universal indicator blue to purple whereas solution B turns universal indicator orange to red.
What sort of reaction takes place when solution A reacts with solution B?
A group of students measured the pH of some substances they found in their homes. Their results are given in the following table:
| Substance | pH | Substance | pH |
| Apples | 3.0 | Salt | 7.0 |
| Baking soda | 8.5 | Sugar | 7.0 |
| Black coffee | 5.0 | Toothpaste | 9.0 |
| Household ammonia | 12.0 | Vinegar | 3.0 |
| Lemon juice | 2.5 | Washing soda | 11.5 |
| Milk | 6.5 |
(a) What would the students have used to measure the pH?
(b) Which solution is the most acidic?
(c) Which solution is the most alkaline?
(d) Which solutions are neutral?
(e) Which solution can be used to treat wasp stings?
(f) Which solutions can be used to treat bee stings?
A student prepares solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?
State whether the following statements are true or false. Correct the false statements.
Phenolphthalein is a natural indicator.
Name any two synthetic acid-base indicators.
Take a small beetroot vegetable and cut it into pieces. Boil them in hot water and filter the extract. Take two test tubes. Take sodium hydroxide solution in one test tube and vinegar or lemon juice in another test tube. Add beetroot extract slowly. Observe the colour change. What do you infer?
