Evaporation Olympics: Which Liquid Disappears Fastest?
Age range: 7–13
Time: 30–60 minutes (plus drying)
Concepts: evaporation, surface area, volatility, temperature
Goal
Compare evaporation rates of safe household liquids and surfaces.
Materials
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Water, vinegar, and isopropyl rubbing alcohol (70%)
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3 identical plates or shallow lids
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Small measuring spoon
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Timer
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Thermometer (optional)
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Fan (optional)
Safety
Use isopropyl alcohol in a well-ventilated area, away from flames. Do not drink any liquids.
Steps
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Equal drops: Place 1 tsp of each liquid on separate plates.
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Start timer: Observe which disappears first at room temperature.
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Surface area test: Spread a new 1 tsp into a thin film vs. a dome; compare times.
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Airflow test: Repeat with a gentle fan at constant distance.
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Temperature test: Warm water slightly (no more than body-warm ~35–40°C) and compare to cool water.
What’s Happening
Evaporation occurs when molecules escape the liquid surface; higher vapor pressure (alcohol), greater surface area, airflow, and temperature all speed it up.
Troubleshooting
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Times too similar? Use smaller amounts (½ tsp) and a fan for clearer differences.
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Uneven surfaces? Use identical, level plates.
Extensions
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Graph evaporation time vs. variable (surface area, airflow).
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Try safe alternatives (salt water, sugar water) to see solute effects.
Try Nex–The Paper Bridge might be another project you would enjoy
