Activity 2.2 Class 10 Science

 In this post, you will find Class 10 NCERT Science Activity 2.2 Explanation in detail. This activity is based on chapter 2 Acids, Bases and Salts of class 10 science.

Testing Acids and Bases using Natural Indicators

Aim of the Activity

 To observe the effect of acids and bases on natural indicators

  

Procedure

1)  Take some finely chopped onions in a plastic bag along with some strips of clean cloth. Tie up the bag tightly and leave overnight in the fridge. The cloth strips can now be used to test for acids and bases.

2)  Take two of these cloth strips and check their odour.

3)  Keep them on a clean surface and put a few drops of dilute HCI solution on one strip and few drops of dilute NaOH solution on the other.

4)  Rinse both cloth strips with water and again check their odour.

5)  Note your observations.

6)  Now take some dilute vanilla essence and clove oil and check their odour.

7)Take some dilute HCI solution in one test tube and dilute HCI and dilute NaOH solutions and record your observation

Observations

 In the above activity the following observations have been observed-  

Onion: Onion has a peculiar smell due to the presence of Sulphurous allium. The smell of onion diminishes in a base because it reacts like acid and remains as it is in acid.

Vanilla essence: Vanilla has a pleasant odour due to the presence of an aldehyde and this is a weak acid so the odour of vanilla essence disappears when it is added to a base.  The odour of vanilla essence persists when it is added to an acid.

Clove Oil: In bases, its characteristic smell cannot be detected.

Test	Effect of Acids (HCl)	Effect of Base(NaoH)
Onion-soaked cloth strip	No significant change in odour	Smell disappears
Vanilla essence	Smell disappears	No change
Clove oil	No change	Smell disappears

Conclusion

 The olfactory indicators change the odour in acidic and basic mediums.

Related Topics -

1. Next activity - Activity 2.3

2. Previous activity - Activity 2.1

2. Solutions of Chapter 2 

3. MCQ Questions of Chapter 2

4. Extra Questions of Chapter 2