✓ Board-verified
Science · 2024 · 5 marks
CBSE 2024 · Region 5 · Set 2 · Q34
(a) Explain chlor-alkali process and write balanced chemical equations for the reactions that occur. Name the gases obtained at the anode and cathode…
(a)
Explain chlor-alkali process and write balanced chemical equations for the reactions that occur. Name the gases obtained at the anode and cathode respectively. Mention two uses each of the two gases obtained in the above process.
OR
(b)
Common salt is a very important raw material as many compounds of industrial use can be prepared from it. Explain, giving chemical equations, the method of preparation of washing soda from sodium chloride. List four industrial/domestic uses of washing soda.
Marking-scheme solution
(a)
• Chlor-akali process - When electricity is passed through aqueous solution of sodium chloride (brine), it decomposes to form sodium hydroxide, chlorine and hydrogen.
\(\displaystyle 2 \mathrm{NaCl}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{NaOH}+\mathrm{Cl}_{2}+\mathrm{H}_{2}\)
Anode - Chlorine gas / Cl2 Cathode- Hydrogen gas/ \(\displaystyle \mathrm{H}_{2}\)
\(\displaystyle \mathrm{Cl}_{2}-1\). Used in the preparation of bleaching powder.
2. To make drinking water free from germs or any other.
\(\displaystyle \mathrm{H}_{2}-1\). Used in the manufacture of ammonia fertilisers. 2. Used in fuels and margarine.
(b) • Concentrated solution of sodium chloride reacts with ammonia and carbon dioxide to obtain sodium hydrogen carbonate and ammonium chloride.
\[\mathrm{NaCl}+\mathrm{NH}_{3}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NaHCO}_{3}+\mathrm{NH}_{4} \mathrm{Cl}
\]
When sodium hydrogen carbonate is heated strongly, sodium carbonate is obtained.
\[2 \mathrm{NaHCO}_{3} \xrightarrow{\text { Heat }} \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}
\]
Sodium carbonate is dissolved in water to obtain washing soda.
\[\mathrm{Na}_{2} \mathrm{CO}_{3}+10 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Na}_{2} \mathrm{CO}_{3} \cdot 10 \mathrm{H}_{2} \mathrm{O}
\]
Uses :
In glass, soap and paper industries
Manufacture of borax
As cleaning agent for domestic purposes.
-For removing permanent hardness of water.
All Acids, Bases and Salts questions2024 question paperNCERT solutions: Acids, Bases and SaltsPractice Acids, Bases and Salts →
More from Acids, Bases and Salts
- Assertion: Concentrated nitric acid is diluted by adding water slowly to acid with constant stirring. Reason (R): Concentrated nitric acid is easily…2025
- Define the following terms: (i) Olfactory indicator (ii) Water of crystallization2026
- An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse the change?2026
- (i) A compound 'X' which is prepared from gypsum has the property of hardening when mixed with proper quantity of water. Identify 'X' and write its…2023
- How is a universal indicator obtained? How is the wide range of pH of solution tested by it?2026
- In the following diagram, if acetic acid of same concentration is taken in place of dilute sulphuric acid, then2026
- Rain water is called 'acid rain' when its:2026
- Which of the given option represents a family of salts?2025
CBSE Class 10 Science past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.