Experiment 7 — Evaporation and the Water Cycle

Topic: Chemistry · Classes 4–5 · States of water: evaporation and condensation

Aim: Evaporate more than 40 ml of water in two hours.

Daily: Wet clothes dry faster on a sunny, windy day and when spread out rather than bunched up. Salt pans, drying papads and a steaming cup of tea are all evaporation at work.

Question: The same water is poured into a wide plate and a narrow glass, both in the Sun. Which loses water faster?

Exp: Evaporation happens at the surface, and the plate exposes far more surface.

Exp: Boiling needs 100 °C; evaporation happens all the time at the surface.

Question: Drops on the underside of a lid form by…

Exp: Vapour cools on the lid and turns back into liquid.

Question: Clothes dry fastest on a day that is…

Exp: Heat plus moving air is the fastest combination.

Question: In the water cycle, what lifts water into the sky?

Exp: The Sun’s heat evaporates water from seas, rivers, soil and plants.