As you may remember, Amy was locked in her lab last month, feverishly working on her science fair project. Now, the results are ready to be seen. Take a look at Amy's work.

Heat and Evaporation

Problem

For the science fair, I've chosen to experiment with evaporation. To do this, I've explored heat and its affect on evaporation rates when water is placed under different wattage bulbs.

For the experiment I used four different watts: a twenty-five watt bulb, a forty watt bulb, a sixty watt bulb, and a seventy-five watt bulb. Each bulb was placed in a rubber light socket and attached to a box where it hung over a glass of eight oz. water.

I decided to do this experiment because of an occurrence at my camp. I go to seven weeks of camp in Belgrade Lakes, Maine. This past summer, the water level of the lake was the lowest it's been since I've been there. We also had only three rainy days the whole summer. Since heat energy causes evaporation, I wanted to know if the great amount of sun had to do with the lack of water in the lake.

Hypothesis

My hypothesis was that the seventy-five watt bulb would cause the most evaporation. The reason for my hypothesis is this. All substances have molecules. These molecules have a certain amount of kinetic energy. The more kinetic energy molecules have, the faster they move allowing them to break free of the bonds that hold them together. Evaporation takes place when molecules of a substance have enough kinetic energy to escape from the substances surface. Kinetic energy comes from heat. Therefore, the more heat a substance obtains, the more kinetic energy it has which causes evaporation. Another way of saying it is, the higher the temperature, the more rapid the evaporation.

Procedure

1. I first went out and bought my materials - light bulbs, four rubber light sockets, nine ounce plastic cups, four 15" by 15" by 15" cardboard boxes, duct tape, and a disposable camera.
2. I then put the boxes together.
3. I measured to the center of the top of the box and placed a dot there.
4. I then poked the light socket through at the dot, making sure that the prong was exactly two and one-half inches above the box.
5. I taped the light to the box in that spot.
6. I then measured to the center of the bottom of the box and placed a dot there.
7. I placed a plastic cup directly on top of the dot making sure that the center of the cup was directly on top of the dot.
8. I then taped the glass down to make sure it wouldn't move.
9. I placed a twenty-five watt bulb in the socket and labeled the box.
10. I put the other three boxes together in the same way. Making sure that the socket was at the same height and place and the same for the cup. Except for the fact that each box had a different bulb and a different label.
11. I filled each glass with eight ounces of water making sure each was the exact same measurement.
12. I kept the light on for thirty hours.
13. I then poured the water back into each measuring cup and recorded the number of ounces that remained.
14. I repeated this experiment four more times in the same exact manner.
15. I recorded all my results.

Observations & Data

This photo shows how the boxes looked in the beginning:

This photo shows how the boxes looked after the thirty hours passed:

This photo shows the control box with water:

There are a few possible errors in my science fair project. The lights could have been at a slightly different angle. This could have effected the amount of heat on a glass of water compared to another. Another possible error is that when pouring the water back into the measuring cup, a little water could have been left over. Even though this could of happened, it would be such a tiny bit of water that I don't think it would have effected the overall results.

I could have improved my experiment by adding a couple more wattages. That would have helped my results even more. I tried to do a one hundred watt bulb, but the socket started to melt and we didn't want the house to burn down! Another way of improving my experiment would be to use actual measuring glasses instead of cups. Then I could have taken daily observations of the actual evaporation.

One new question formed in my head while I was doing this experiment. Another idea is to not only test the evaporation of water with different wattage bulbs, but you could also test the angles of which the bulbs are placed. Then you could use it as a replica of the sun and see what time of day the most evaporation takes place. That would be most interesting.

Conclusions

My hypothesis was correct. The seventy-five watt bulb caused the greatest amount of evaporation. In the first test, there was five and one-half ounces of water left. In the second test, there was five and one- quarter ounces of water left. In the third test, there was five and one -quarter ounces of water left. In the fourth test, there was five and one-half ounces of water left. In the fifth test, there was five and one-half ounces of water left. Over all the average rate of evaporation was 2.6%. The average rate of evaporation for sixty watt bulbs was 1.85%. The average rate of evaporation for forty watt bulbs was 1.65%. The average rate of evaporation for twenty-five watt bulbs was 1.45%. It is obvious that the seventy-five watt bulb caused the most evaporation. This is because again, the more heat a substance has, the more kinetic energy and it is kinetic energy which is the cause of evaporation.