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|| WHAT IS EVAPORATION?
Design tests to find out how each of the following factors
affects the rate at which water evaporates:
Does hot water evaporate faster than cold water? When we
wash dishes and leave them in a drainer for Mother Nature to
dry them, is there a difference if we rinse in cold water as
opposed to hot water?
2) movement of the air:
If there is a fan blowing across the liquid, what effect will
the moving air have on the evaporation rate?
3) kind of liquid:
Does cooking oil evaporate slower or faster than water? How
about rubbing alcohol?
4) amount of moisture in the air (humidity):
On a high humidity day, would evaporation of water be slower
Prepare at least two conditions for each test, so that
results can be compared. For example, to test the effect of
air movement, place some liquid in front of an electric fan
and an equal amount in another place where there is no wind
but the temperature and humidity are the same.
Observe saucers filled with water over a period of several
days. Keep a daily record of what happens to the water.
Fill a flower pot with soil, and pour water into the soil
until it begins to drip from the bottom. Weigh the pot, then
do not water it again for a week. After a week, weigh the
pot again. Compare the before and after weights of the pot.
What caused the difference?
Pour 1/2 cup of water into each of two identical shallow
pans. Place one pan in a warm location and the other in a
cool place away from any breeze. Compare the time required
for the water to evaporate from each pan. Make some judgment
about the relationship of heat to evaporation.
The test can be repeated and speeded up by placing the
experimental pan over a heat source such as a hot plate or
radiator. Similarly, two cloths of the same size and the
same material can be substituted for the pans. Soak each
cloth thoroughly in water. Set one cloth in a cool location
and the other in a warm location. An analogy can be made to
clothes on a clothesline on a sunny day and on a cloudy day.
In each of the above tests, be sure that the heat factor is
the only influence.
Pour one cup of water into a wide, shallow dish and another
cup of water into a tall, narrow jar. Place both in direct sunlight. You will see that the water in the dish with the
wide mouth evaporates faster than the water in the jar. Discuss differences in evaporation from small puddles and large
lakes. Does ocean water evaporate?
Where does liquid go after it evaporates?
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