Question

(a) Balance the following chemical equation:
$\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\stackrel{\mathrm{heat}}{\to }\mathrm{PbO}\left(\mathrm{s}\right)+{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$
(b) State two characteristic features of carbon which when put together give rise to a large number of carbon compounds.
​(c) Describe an activity to show that acids produce ions only in aqueous solutions.

Answer 1

(a) $2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\stackrel{\mathrm{heat}}{\to }2\mathrm{PbO}\left(\mathrm{s}\right)+4{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

(b) Feature of carbon which gives rise to a large number of carbon compounds:
1. Catenation: Is is the ability of carbon compounds to form long chains, branched chains.
2. Smaller nucleus helps it to attract a number of electrons.

(c)
Procedure:
1. Take about 1 g of sodium chloride in a clean and dry test tube.
2. Add some concentrated sulphuric acid.
3. A gas is produced and comes out through the delivery tube.
4. Test the gas evolved with dry and wet strips of litmus paper.



Observation:
1. When the gas evolved is passed through dry litmus paper, there is no change in the colour of litmus paper.
2. However, when the gas is passed through wet blue litmus paper, the paper turns red, which indicates that the gas evolved is an acid.

Conclusion:
This activity concludes that hydrogen ions in hydrochloric acid are produced in the presence of water because only wet blue litmus turns red.