MediumChemistryHigh School (9–10)GeneralStates of Matter › Evaporation and CoolingConceptualBoard Exam
On Tuesday it is sunny and windy, and a wet cloth dries in 2 hours…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
On Tuesday it is sunny and windy, and a wet cloth dries in hours. On Wednesday it rains all day, and the same wet cloth is still damp in the evening. Give three reasons for the difference.
Need a reminder? The key ideaShow
Evaporation is the change of a liquid into a gas at its surface, at any temperature. It is faster with a larger surface, a higher temperature, a lower humidity and more wind. Boiling happens all through the liquid, at the boiling point, with bubbles.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Humidity. On the rainy day the air is full of water vapour, so it takes in very little more.
Step 2. Wind. On Tuesday the wind carries the vapour away from the cloth, so the air next to it stays dry. On the still, rainy day the vapour stays around the cloth.
Step 3. Temperature. The sunny day is warmer, so more particles of water have enough energy to escape.
Answer: On Wednesday the humidity is higher, there is less wind, and it is cooler. All three slow evaporation.
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