Equilibrium Between Nitrogen Dioxide and Dinitrogen Tetroxide
Description: Heating and cooling flasks of NO2 and N2O4 shift the equilibrium between the two species. When more NO2 is produced, the color of gas inside the flask becomes darker.
Source: Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry
Year: 1985 Vol: 2 Page: 180
Ratings: 
Keywords: Equilibrium, Dinitrogen tetroxide, Nitrogen dioxide, Temperature, LaChatelier’s Principle, Raoult’s Law, Beer’s Law
Hazard: Medium
- Use of toxic gas – sealed vessels
- Demo at non-standard conditions
- Electric shock hazard
- Asphyxiation hazard
- Flammable liquids when acetone bath is used
- Eye irritation
- Cryogenic burn hazard
- Specific organ toxicity – central nervous system when acetone bath is used
Effectiveness: Good
- Results are clearly observable with guidance
- Good connection from demo to course material
- Clear contrast between behavior of systems
- Time to results is medium
- Mild effects are seen by audience
Difficulty: Medium
- Physical manipulation of reagents – use of hot bath and cold bath
- Handling of toxic reagents
- Procedure with some intermediate steps
- Temperature dependent results
Safety Precautions:
- Perform in a well-ventilated area
- Eye protection required
- Temperature-resistant gloves required
- Use of UL approved three-prong plug and outlet
- Absorbent material on hand
- ABC fire extinguisher on hand
- Avoid exposure to droplets, mists and vapors
- Handle gas flasks with care
Class: Equilibrium, Gases, Entropy, Thermodynamics, Groups IVB and VB (under 14 and 15)
Division: General, Inorganic Chemistry, Physical Chemistry
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