Equilibrium of Chemical Systems- Equilibrium Between Nitrogen Dioxide and Dinitrogen Tetroxide

Water Cryophorus Tube

Equilibrium Between Nitrogen Dioxide and Dinitrogen Tetroxide

Effect of Pressure on Melting Point of Ice

Ice Bomb

The Liquid Phase of Carbon Dioxide

Vapor Pressure of Pure Liquids

The Drinking Bird

Getting Colder: Freezing-Point Depression

Getting Hotter: Boiling-Point Elevation by Nonvolatile Solutes

Model of Osmotic Pressure

Osmotic Pressure of a Sugar Solution

Vapor Pressure of Solutions: Raoult’s Law

Volume Decreases Upon Mixing

Boiling Two Liquids at Room Temperature

Salting Out: Making Liquids Immiscible

Making Liquids Immiscible II

Aluminum & Oxygen Battery

Cathodic Protection

Concentration Cell

Electrolysis of Potassium Iodide

Electrolysis of Water

Voltaic Cells

Display Batteries

Fuel Cell

Hydrogen Ion Concentration Cell

Acid-Base Properties of Amino Acids

Electrical Conductivity of Liquids and Solutions

Instrumental Recording of a Titration Curve

A Visual Demonstration of Raoult’s Law

Equilibrium Between Nitrogen Dioxide and Dinitrogen Tetroxide

A set of three flasks of brown gas. Two are in water baths. In the second photo, a wooden clamp holds a flask with brown gas in front of a beaker with ice water, and a wooden clamp holds a beaker with dark brown gas in front of a beaker with clear liquid. A larger flask with brown gas appears between two flasks. The relative colors of the flasks have changed.
A set of three flasks of brown gas. Two are in water baths. In the second photo, a wooden clamp holds a flask with brown gas in front of a beaker with ice water, and a wooden clamp holds a beaker with dark brown gas in front of a beaker with clear liquid. A larger flask with brown gas appears between two flasks. The relative colors of the flasks have changed.
 

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 – CNS 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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