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#### 2. State the method of testing the following gases and their properties: 1. **co₂(g)** 2. **nh₃(g)** 3. **no₂(g)** 4. **hydrogen Gas** 5. **hydrogen Sulphide Gas**
Accepted Answer
Here are some methods for testing the listed gases and their properties:
1. CO₂(g):
- Limewater test: Pass the gas through limewater (Ca(OH)₂ solution). CO₂ reacts with limewater to form a white precipitate of calcium carbonate (CaCO₃):
CO₂(g) + Ca(OH)₂(aq) → CaCO₃(s) + H₂O(l)
- pH test: CO₂ dissolves in water to form carbonic acid (H₂CO₃), which is acidic. You can test the pH of the solution with pH paper.
2. NH₃(g):
- Litmus paper test: NH₃ is a base. It turns red litmus paper blue.
- Smell: NH₃ has a characteristic pungent odor.
3. NO₂(g):
- Color: NO₂ gas is reddish-brown.
- Smell: NO₂ has a pungent, suffocating odor.
4. Hydrogen Gas:
- Burning test: Hydrogen gas burns with a pale blue flame. It reacts with oxygen to form water:
2H₂(g) + O₂(g) → 2H₂O(g)
- Pop test: If a burning splint is inserted into a test tube containing hydrogen gas, it will produce a 'pop' sound.
5. Hydrogen Sulphide Gas:
- Smell: H₂S has a rotten egg odor.
- Lead acetate paper test: H₂S reacts with lead acetate paper to form a black precipitate of lead sulfide (PbS):
H₂S(g) + Pb(CH₃COO)₂(aq) → PbS(s) + 2CH₃COOH(aq)
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