Purpose :- :- :- :-
The purpose of this experiment was to compare the effect of wind speed, air humidity, and water temperature on the evaporation rate of water.
I became interested in this idea because I knew that water evaporation could be helpful when it cooled you down and harmful when it dehydrated both plants and people, so I decided to learn more about what affected evaporation.
The information gained from this experiment could help food producers who dehydrate fruit, vegetables, or meat. It could also help coaches and athletes who need to keep cool during strenuous exercise, and people who are interested in outdoor activities, such as camping, hiking, or swimming.
My
hypothesis was that the temperature of the air would affect evaporation rate
most.
I based my hypothesis on a diagram I found in Young Scientist Encyclopedia. The diagram showed that the warmer the water, the more molecules escaped as vapor.
I also based my hypothesis on a
slideshow I saw on the movie “Bill Nye the Science Guy: The Water
Cycle.” It showed that boiling water’s molecules have more energy
and escape as vapor at a much faster pace than molecules at room temperature.
The constants in this
study were
• The type of water (tap)
• The amount of
water
• The location the
water is placed
• The size of the
container
• The ruler
• The number of
trials conducted
• The type of the
container
• How long the water
has to evaporate
The manipulated variables were air humidity, wind speed, and water temperature.
The responding variable was the amount of water evaporated in 150 minutes. I measured the water in a graduated cylinder before and after the evaporation occurred.
To measure the responding variable, I measured the water in milliliters before and after the evaporation occurred.
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Quantity
|
Item Description
|
|
1
|
Small
room fan
|
|
3
|
Liters
tap water
|
|
5
|
Small
dishes
|
|
1
|
Small
air humidifier
|
|
1
|
100
ml. graduated cylinder
|
|
1
|
Humidity
meter
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|
1
|
Room
thermometer
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|
1
|
Lab
thermometer
|
|
1
|
Plastic
jug (approx. 4 liters)
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Procedures
1.
Collect materials.
2. Stabilize and maintain the humidity in testing room using a small air humidifier as needed. For the first phase of testing, the humidity should be about 34%.
3. Stabilize and maintain the temperature in testing room. For the first trials the room temperature should be 10º C.
4. Stabilize and maintain the air speed in testing room using a small fan as needed. For the first trials the wind speed should be “dead calm”.
5. Place a jug of tap water in the testing room so it adjusts to the room temperature. Whenever the water temperature is the same as the air temperature, the experiment can continue.
6. Pour 100 ml. of tap water from the jug at the current temperature into each of 5 identical small dishes using a graduated cylinder.
7. Place the dishes so they are being equally affected by room temperature, humidity, and air movement.
8. Using a timer, let the water sit in the testing room for 180 minutes.
9. Using a graduated cylinder, measure the water remaining from each dish and subtract each from the original 100 ml.
10. Record this as how many milliliters evaporated for that trial.
11. Repeat steps 4-10, except turn the fan on to its high-speed setting. Be careful when placing the dishes that all are equally affected by the moving air.
12. Repeat steps 3-11, but stabilize and maintain the temperature at 20º C.
13. Repeat steps 3-11,
but stabilize and maintain the temperature at 30º C.
14. Repeat steps 2-13, but stabilize and maintain the humidity at about 65% for the entire series of trials.
The
original purpose of this experiment was to compare the effect of wind speed,
air humidity, and water temperature on evaporation rate of water.
The results of the experiment were
that wind speed affected evaporation rate most. The difference between
the two wind speeds evaporated water is 4.4 ml.
Conclusion
My hypothesis was that the temperature
of the air would affect evaporation rate most.
The results indicate that this
hypothesis should be rejected, because wind speed affected evaporation rate
most. The temperature of the air did not matter nearly as much as the
wind speed and air humidity in the room when you are testing evaporation rate.
After thinking about the results of
this experiment, I wonder if the size of the room would affect how much water
was evaporated. Water in dishes set in a closet might evaporate very
differently than in a gymnasium. All liquids can evaporate but they do so
at varying rates. It would be interesting to see what happens to a fast
evaporating liquid like rubbing alcohol using my same procedures.
If I were to conduct this project
again, I would do many more trials of each variation. I would still use
five dishes at a time, but I would do at least three different batches of five
for each temperature, wind speed, and humidity condition. I am sure that
each evaporation trial should have been much longer, probably five to eight
hours long. That would have given a better idea of what happened with
each condition. It would also have been better to add an intermediate
wind speed, about halfway between high and zero.
Researched by ------ Kaiti D
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