Nitrogen cannot be stored as liquid in sealed containers but ammonia can be, why

Explanation

To understand why nitrogen cannot be stored as a liquid in sealed containers while ammonia can, we need to look into the concept of critical temperature and its implications on the storage of gases.

### Step-by-Step Solution:

1. **Understanding Critical Temperature**:
- The critical temperature of a substance is the highest temperature at which it can exist as a liquid, regardless of the pressure applied. Above this temperature, the substance cannot be liquefied by pressure alone.

2. **Critical Temperature of Nitrogen**:
- Nitrogen (N2) has a very low critical temperature, approximately -146°C (-234°F). This means that at temperatures above this, nitrogen cannot be liquefied, even under high pressure.

3. **Critical Temperature of Ammonia**:
- In contrast, ammonia (NH3) has a much higher critical temperature, around -33°C (-27°F). This allows ammonia to be stored as a liquid at higher temperatures compared to nitrogen.

4. **Implications for Storage**:
- Since nitrogen's critical temperature is so low, any increase in temperature (even slightly above -146°C) will cause nitrogen to vaporize into gas, making it impossible to maintain it in a liquid state in a sealed container.
- On the other hand, ammonia can remain in a liquid state at higher temperatures, making it feasible to store it in sealed containers without it turning into gas.

5. **Conclusion**:
- Therefore, the key reason why nitrogen cannot be stored as a liquid in sealed containers while ammonia can is due to the significantly lower critical temperature of nitrogen compared to ammonia.