Sodium Hydroxide (Preparation) MCQs Quiz | Class 10
Test your understanding of Class X Science (Code 086), Unit I: Chemical Substances – Nature and Behaviour. This quiz focuses on the preparation of Sodium Hydroxide via the Chlor-alkali process, covering reaction details, raw materials, and by-products. Click ‘Submit Quiz’ to check your score and download the PDF solution sheet.
Overview of Sodium Hydroxide Preparation
Sodium Hydroxide (NaOH), commonly known as Caustic Soda, is a vital industrial chemical. It is prepared commercially by the electrolysis of an aqueous solution of sodium chloride (called brine). This method is widely known as the Chlor-alkali process because of the products formed: Chlor for chlorine and alkali for sodium hydroxide.
The Chlor-Alkali Process
When electricity is passed through brine, it decomposes to form sodium hydroxide. The reaction takes place in an electrolytic cell.
General Reaction:
2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g) + H2(g)
Key Products and Their Formation
- Chlorine gas (Cl2): Released at the Anode (positive electrode).
- Hydrogen gas (H2): Released at the Cathode (negative electrode).
- Sodium Hydroxide (NaOH): Formed near the Cathode.
Uses of Products
| Product | Common Uses |
|---|---|
| Hydrogen (H2) | Fuels, margarine, ammonia for fertilizers. |
| Chlorine (Cl2) | Water treatment, swimming pools, PVC, disinfectants, CFCs. |
| Sodium Hydroxide (NaOH) | De-greasing metals, soaps and detergents, paper making, artificial fibers. |
Quick Revision Points
- The raw material used is Brine (saturated salt water).
- The process is endothermic regarding energy input (electricity).
- All three products (H2, Cl2, NaOH) are industrially useful.
Extra Practice Questions
- Why is the process called Chlor-alkali? (Answer: Because of the products Chlorine and Alkali/NaOH).
- What happens if the chlorine and hydrogen gases react directly? (Answer: They form Hydrogen Chloride gas, HCl).
- Is Sodium Hydroxide an acid or a base? (Answer: It is a strong base/alkali).
- Where does the sodium ion (Na+) go during electrolysis? (Answer: Towards the cathode).
- What is the physical state of Sodium Hydroxide produced? (Answer: Aqueous solution).
