Moment of Science
Earth Day is coming up on April 22nd and we want to start the celebration with a clean water experiment! Can you think of a way to clean dirty water using the sun? Do you think you can remove salt from water using the sun? Try your best by making a “solar still” and see how the sun can help make clean water!
First, gather your materials:
- A wide plastic basin
- A smaller jar or glass for collecting the clean water
- A large piece of transparent plastic—plastic wrap works
- String or rubber band to hold plastic in place
Then, follow these instructions:
- Mix salt into some tap water and put the salty water in the bottom of the plastic basin.
- Place the collecting jar in the middle of your basin. Make sure the water is below the height of your collecting jar.
- Cover the basin with plastic wrap. Make sure it’s secured tightly around the edges. Use a string or rubber band to seal the plastic wrap around the edges of the plastic basin.
- Place a stone in the middle of the plastic wrap just above your collecting jar.
- Carefully move your solar still into the sun and let it sit for about half an hour, then record your observations.
- After a few hours return to your solar still and see if anything has changed, there should be more water in the collecting jar. Document your
- After a few hours, when you take your solar still apart, taste the water in the collecting jar. What do you notice? Is the water still salty? How did the water get into the collecting jar? Write down your theories!
So how does it work? When water evaporates it leaves behind any impurities like salt and bacteria. Only pure water evaporates and is condensed on the plastic wrap, it then drips into the collecting jar leaving the water salt free!