Acids and Bases- Invisible Painting

Invisible Painting

Description: A design or picture is painted on absorbent paper with colorless indicator, usually phenolphthalein or thymolphthalein. When it is sprayed with base, the picture appears. Both red and blue colors can be produced.

Source: Shakharshiri B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry

Year: 1989   Vol: 3    Page: 47

Keywords: Phenolphthalein, Thymolphthalein, Indicator, Base, Painting

Rating:

Hazard: Some

• Acute toxicity hazard
• Germ cell mutagenicity
• Corrosive to metals
• Skin corrosion hazard
• Serious eye damage

Effectiveness: Average

• Results are clearly observable without guidance
• Somewhat connected conceptually to course material
• Contrast between systems is noticeable
• Time to results is low
• Mild effects are seen by audience
• Good reliability

Difficulty: Low

• Simple manipulations for most to perform
• Demos do not involve deep attention
• Simple procedures

Safety Precautions:

• Eye protection required
• Gloves required
• Absorbent materials on hand
• Sodium bicarbonate on hand

Class: Acids and Bases, Indicators

Division: General

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