Electrochemical Writing
Description: Filter paper is soaked in potassium Iodide (KI) solution, and phenolphthalein is taped to a backing of aluminum foil. Using a copper wire as a stylus connected to a battery to form a circuit, one can write on the filter paper. Reversing the polarity causes the writing to become another color.
Source: Harris, Daniel Quantitative Chemical Analysis 5th Edition
Year: 1991 Vol: N/A Page: 446
Keywords: Electrochemistry, Circuit, Polarity, Indicators, KI, Battery
Ratings: 
Hazard: Some
- Acute toxicity hazard
- Carcinogenicity hazard
- Reproductive toxicity hazard
- Germ cell mutagenicity hazard
- Specific organ toxicity – thyroid
Effectiveness: Good
- Clear contrast between systems behavior
- Good connection from demo to course material
- Time to results is low
- Moderate failure rate
Difficulty: Medium
- Careful manipulations required
- Some concerted efforts or timed manipulations
- Procedures with some intermediate steps to results
- Use of toxic reagents
- Prior practice recommended
Safety Precautions:
- Eye protection required
- Gloves required
- Absorbent materials on hand
- Avoid exposure to mists, droplets, or vapors
Class: Electrochemistry, Redox, Indicators
Division: General, Analytical Chemistry
Home| General Chemistry Demos| Analytical Chemistry Demos