Science Buddies: "Ask an Expert"

My daughter is working on salt water desalination project. She is trying to correlate the temperature of water v/s yield. In other words, she has multiple kits containing water at different temperatures (Room, 40, 60, 80, 100) and she is trying to understand the rate of increment (in output) when all kits are exposed to sunlight for the same period of time. Does anyone have any comments or analysis of expected outcome? The cost of energy to preheat water v/s benefits (more yield of fresh water) may be the next step in this project.

Thank you in advance.

Hi! I am so glad your daughter is taking on such a cool project. I am assuming, based on your description, that you are working on the Solar-Powered Water Desalination experiment (https://www.sciencebuddies.org/science- ... #procedure) and have already built the desalination kits. If you have already formed a hypothesis, the next step is now to test those kits by following the detailed procedures located at the link above. They can be found by scrolling a little past halfway down under the heading "Testing the Desalination Devices." Make sure to record the time, temperature and condensation of each kit (try to keep the time the same for each kit as it serves as an important control variable here). You can also test the saltiness of each condensate by tasting it.

Again, make sure to record any and all observations you make during the process. Then, repeat the experiment a few times on different days to solidify your results. Finally, once you have carefully collected all of your data, you can graph it as described in the procedures and analyze it by answering the given questions. In your post, you mentioned something about expected outcome. I am assuming that you are wondering about forming your experimental hypothesis. This is an "If, then" statement that basically states what you predict the experiment will show. This should be based on your research and should refer to your independent and dependent variables. This link should help you more with forming and understanding your hypothesis: https://www.sciencebuddies.org/science- ... esis.shtml.

I hope I answered your questions. Good luck with your experiment!
Trystan

Hi Trystan,

Thank you for your detailed response. Her hypothesis is "if we preheat salt water at different temperatures, and then expose it in sunlight (using desalination device/kit purchased from sciencebuddies.org), then the yield will be x% higher when these kits are exposed in sunlight for the same duration of time"

Do you have any comments on how temperature of input should affect the outcome (amount of fresh water)? Keeping cost of energy in heating up the water out of the equation, is there an ideal temperature that will yield the best results?

For e.g. by desalinating water at room temperature through normal process of evaporation/condensation in sunlight yields 2-3 ml of fresh water in 2 hours. Do you expect twice the yield if water is preheated to 80 degrees?

Hello,

Are you trying to determine if the rate of the desalination process will be different, or the total volume of water regardless of the rate? If the water is pre-heated, I would expect the rate to be much higher, but the total water volume that you accumulate in the end should be the same. Let us know!

Best,
Pharma