Activity 2.11 Class 10 Science

This activity explains the acidic, basic or neutral nature of different substances using `P^H` paper. `P^H` paper changes its colour when comes in contact with different substances.

Find the Nature of Different Substances Using `P^H` paper

Aim of the activity

To test the `P^H` value of different substances and find the nature

Materials used in this activity

   1.   `P^H` paper

   2. Different substance (given in the table)

   3. Universal indicator stripes

   4.  Dropper

   5. Watch glass

 

Procedure

We collect samples of substances given in the table below in separate watch glasses. Now we dip fresh `P^H` papers in  the substances and observe the colour change.

Now we match the colour of `P^H` paper with the universal indicator strip and note down the `P^H` values. On the basis of `P^H` scale, we classify the given substances into acidic, basic or neutral and record in the table below.

Table

S. No.	Solution	Colour of pH paper	Approximate pH value	Nature of substance
1 2 3 4   5 6 7 8 9 10	Saliva (before meal) Saliva (after meal) Lemon juice Colourless aerated drink Carrot juice Coffee Tomato juice Tap water 1M NaOH 1M HCI

 

Observation

S. No.	Solution	Approximate pH Value	Nature of substance
1 2 3 4 5 6 7 8 9	Saliva Lemon juice Colourless aerate drink Carrot juice Coffee Tomato juice Tap water 1 M NaOH 1 M HCI	6.5 to 7.5 2.2 to 2.4 5.9 to 6.0   6.4 to 6.6 4.5  to 5.5 4.1 6.9 to 7 14 0	Neutral Acidic Acidic Acidic Acidic Acidic Neutral Basic Acidic

 

Explanation

`P^H` paper changes its colour on the basis of change in hydrogen ions concentration.

A `P^H` value less than 7 indicates acidic nature.

A `P^H` value more than 7 indicates basic nature.

A `P^H` value of 7 indicates neutral nature.

Conclusion

 So, we can conclude that everyday substances have different `P^H` values and nature.

Frequently Asked Questions

1. What is `P^H`?

Answer - `P^H` is a measure of how acidic or basic a solution.

2. Why does saliva have different `P^H` before and after meals?

Answer – Saliva becomes acidic after meal and it is alkaline before meal. So, it has different `P^H` values.

3. Why is 1M HCl considered a strong acid?

Answer – Because it completely dissociates in water and release high concentration of hydrogen ions.

4. Why does NaOH have a high `P^H`?

Answer – It release maximum hydroxide ions in water so it has high `P^H` value.

5. Can we use `P^H` testing in agriculture?

Answer -  Yes, we can use `P^H` testing in agriculture because it is suitable to determine the `P^H` of soil.

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4	Activity 2.4
5	Activity 2.5
6	Activity 2.6
7	Activity 2.7
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