This activity belongs to chapter 2 Acids, Bases and Salts Class 10 Science
Do All Acids Produce Ions only in Aqueous Solution?
Aim of the activity
To observe what happened to an acid or a base in water solution and find if acids produce ions only in aqueous solution.
Material used in the activity
1. Solid sodium chloride (NaCl) 1 g
2. Concentrated sulphuric acid
3. Test tubes
4. Blue Litmus paper
5. Delivery tube
6. Dropper
7. Clamp stand
8. Guard tube containing `CaCl_2`
Procedure
We take about 1g solid `NaCI` in a clean and dry test tube and set up the apparatus. We then add some concentrated sulphuric acid to the test tube. As the reaction begins, a gas evolve and come out of thedelivery tube.
We bring a dry blue litmus paper strip close to the mouth of the delivery tube and observe any colour change.
Next, we bring a moistened blue litmus paper strip close to the mouth of delivery tube and observe the colour change.
Note to teachers : If the climate is very humid, you will have to pass the gas produced through a guard tube (drying tube) containing calcium chloride to dry the gas].
Observation
A colourless `HCl` gas evolve on the reaction of NaCl and H2SO4
When we bring dry blue litmus paper near the opening of the calcium chloride tube, colour of the litmus paper remains unchanged.
But when we bring a moistened blue litmus paper near the mouth of delivery tube, blue litmus changes to red.
Explanation
HCl gas is produced on the reaction of NaCl and H2SO4
NaCl + H2SO4 → NaHSO4 + HCl↑
This HCl gas does not show any effect on dry blue litmus paper. But it ionize with wet blue litmus paper and the blue litmus paper changes to red
HCl + H2O → H3O+ + Cl–
Conclusion
Dry HCl gas has no effect on dry blue litmus paper. But in the presence of moisture, hydrogen chloride gas turns blue litmus to red. Thus HCI gas shows its acidic character only in presence of water.
Frequently Asked Question
1. Whydoes dry `HCl` gas not show acidic character?
Answer
Dry HCl gas does not produce ions so it does not show acidic character.
2. What type of reaction occurs between NaCl and H2SO4 ?
Answer
The reaction is double displacement reaction.
3. Can this activity be performed with other acids?
Answer
Yes , this activity can be performed with other acids also because all acids release ions in water.
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