Equilibrium Between Nitrogen Dioxide and Dinitrogen Tetroxide
Effect of Pressure on Melting Point of Ice
The Liquid Phase of Carbon Dioxide
Vapor Pressure of Pure Liquids
Getting Colder: Freezing-Point Depression
Getting Hotter: Boiling-Point Elevation by Nonvolatile Solutes
Osmotic Pressure of a Sugar Solution
Vapor Pressure of Solutions: Raoult’s Law
Boiling Two Liquids at Room Temperature
Salting Out: Making Liquids Immiscible
Electrolysis of Potassium Iodide
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
Electrolysis of Water
Description: A standard Hoffman apparatus demonstration. Voltage is applied to the system, and water is broken down into hydrogen and oxygen. The relative amount of each gas is 2:1. Bromothymol blue indicator is mixed into the solution. The solution turns blue (basic) on the side that hydrogen is produced, and yellow (acidic) on the side that oxygen is produced.
Source: Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry
Year: 1991 Vol: 4 Page: 156
Keywords: Electrolysis, Hoffman apparatus, Acids, Bases, Indicators
Rating: 
Hazard: Some
- Electrocution hazard
- Flammability hazard
- Flammable gas-producing reaction
- Explosion hazard
Effectiveness: Average
- Good connection from demo to course material
- Results are observable with guidance
- Mild effects are seen by audience
- Time to results is high
- Good reliability
Difficulty: Medium
- Procedures with some intermediate steps to results
- Manipulations are simple for most to perform
- Use of scientific glassware
- Sequential or timed manipulations
- Prior training recommended
Safety Precautions:
- Eye protection required
- Perform in a well-ventilated area
- Use of UL approved three-prong plug and outlet required
- ABC fire extinguisher on hand
- Use caution when handling flammable gas
Class: Electrochemistry, Electrolysis, Acids and Bases
Division: General, Analytical Chemistry, Physical Chemistry
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