Science Buddies: "Ask an Expert"

I would like some help with the design of my water evaporation experiment which is due on Monday. My hypothesis is that the greater the surface area of a container of water, the faster the evaporation rate. If I use two different size containers such as a small glass measuring cup and a shallow glass pie plate how would I measure the evaporation of the water? Would I use a scale, like a kitchen scale (which I would have to buy)? How much water should I use to get results over an 8-10 hour period? Would it work to use graduated cylinders and cover part of the top of one with aluminum foil or another material to reduce the surface area? Or does the surface area difference have to be bigger to produce usable data? Also, what type of water? Tap, bottled or distilled? Or does it matter? What recommendations do you have? I hope you can answer me as soon as possible. Thank you very much for your help.

Hi Jua,
Three days is a very brief time to design and conduct an experiment. I would recommend using wide and shallow containers so that you see a large relative change in mass. If you have a sensitive scale that can measure the change in mass (I'm not sure if a kitchen scale will suffice) that seems best. If not, then you can try to transfer the water into a graduated cylinder to measure the change in volume. I think distilled water would be best, because you aren't interested in any possible effects of solutes, but tap water should be fine too.
I hope that helps. good luck!
Chris

1 thing you could do is...
Take amounts volumes of WATER and pour em in diffent containers which gaurentee different surface areas. and one way you can measure the rate is, note the time for the entire water to get evaporated. or subject the two samples for same amount of TIME and then measure the volume remaining of the TWO samples.

Remember that its most important to keep all your variables constant. If you use distilled water in one, its okay to use distilled water in another.

As for measuring surface area, if you take a cylinder for example, measure the diameter, divide it by 2, square it * pi (3.14159) and you will get the surface area of the water in the cylinder exposed to air.

As for how much we should expect to evaporate after a given amount time, you tell us! You are the expert here .