demonstrations:hot_water_condensation

Hot Water Condensation

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★★☆ Some safety precautions required to perform safely

Categories: Particles and States of Matter, Water Cycle

Alternative titles: Water Cycle Condensation

Summary

This experiment demonstrates condensation, a key stage in the water cycle. By placing an upside-down cup with an ice cube over a cup of hot water, students can observe how water vapor cools and condenses into liquid droplets, similar to how clouds form in the atmosphere.

Procedure

  1. Boil water and carefully pour it into a transparent plastic cup until it is two-thirds full.
  2. Place a second cup upside down over the hot water cup.
  3. Balance an ice cube on top of the inverted cup.
  4. Watch closely as condensation forms inside the upper cup.
  5. Observe how small droplets gradually combine into larger ones, mimicking how clouds form.

Condensation Experiment | The Water Cycle - Hannah Leake:


Variations

  • Try using multiple ice cubes to see if condensation increases.
  • Test with warm water instead of hot to compare how quickly condensation occurs.

Safety Precautions

  • Handle boiling water carefully to avoid burns.
  • Adult supervision required for younger students.
  • Ensure the cup with hot water is stable to prevent spills.
  • Be cautious when balancing the ice cube to prevent slipping accidents.

Questions to Consider

  • Why does condensation form inside the second cup? (Because water vapor from the hot water cools against the cold surface, turning back into liquid droplets.)
  • How is this similar to cloud formation? (Clouds form when warm, moist air rises, cools, and condenses into water droplets.)
  • What would happen if you used cold water instead of hot? (Much less vapor would form, so condensation would be minimal or absent.)
  • Why do the small droplets eventually merge into larger ones? (Water molecules attract each other, causing droplets to coalesce.)