Question: describe a simple test for the presence of nitrogen gas

Jacinta Nzilani answered on 16 Jul 2025:

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Hey! 👋 Here’s how you can test for Nitrogen gas (N₂)

🧪 Nitrogen is not tested directly, but we identify it using these properties:
1. It is colorless, odorless, and tasteless

2. It is slightly less dense than air

3. It is unreactive

4. It does not support combustion

Test 1: Glowing Splint Test 🔥

🔬 Procedure:
Collect the unknown gas in a test tube.

Light a wooden splint and blow it out so it’s glowing.

Insert the glowing splint into the gas.

🔍 Observation:
The glowing splint goes out.

✅ Conclusion:
The gas does not support combustion → It could be nitrogen.

❗ Note: CO₂ also gives the same result, so this test is not specific.
🧠
🔥 Splint goes out!

Test 2: Preparation and Identification of Nitrogen by Removal of Oxygen from Air

We can prepare nitrogen by removing oxygen from air using hot copper metal.
2Cu(s) + O₂(g) → 2CuO(s)
Copper reacts with oxygen.

Nitrogen is left behind because it doesn’t react.

✅ Conclusion:
The gas that remains after removing oxygen from air is mostly nitrogen (since air is about 78% nitrogen).

It doesn’t support burning.

It’s unreactive → likely to be nitrogen gas.