Acids, Bases and Salts | Class 10 | Activity 2.9 with Solution

Activity 2.9  

• Take about 1g solid NaCl in a clean and dry test tube and set up the apparatus as shown in Fig. 2.4.
• Add some concentrated sulphuric acid to the test tube.
• What do you observe? Is there a gas coming out of the delivery tube?

✅ Answer: HCl gas comes out of the delivery tube.

• Test the gas evolved successively with dry and wet blue litmus paper.
• In which case does the litmus paper change colour?

✅ Answer: When HCl gas is tested with wet blue litmus paper, it becomes red colour. But with dry litmus paper, no colour change occurs.

• On the basis of the above Activity, what do you infer about the acidic character of:
• (i) dry HCl gas
• (ii) HCl solution?

✅ Answer: (i) dry HCl gas cannot produce H⁺ ions. So it does not behave as an acid.  

(ii) HCl solution can produce H⁺ ions and behave as an acid.

HCl + H₂O → H₃O⁺ + Cl^–

Fig. 2.4

• Activity 2.1
• Activity 2.2
• Activity 2.3
• Activity 2.4
• Activity 2.5
• Activity 2.6
• Activity 2.7
• Activity 2.8
• Activity 2.9
• Activity 2.10
• Activity 2.11
• Activity 2.12
• Activity 2.13
• Activity 2.14
• Activity 2.15

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