Most of the water on Earth is contained in the ocean. We can’t drink this saltwater, but the ocean does provide much of our drinking water. How is this possible. Through the water cycle of course!
Water from the ocean evaporates and then falls back to the earth in the form of rain. Kids can see this on a small scale by creating a solar still.
In a solar still, water warms up and forms a gas. The gas rises to the plastic wrap and condenses into water drops. These drops roll down the plastic wrap and are collected in a small container in the middle of the still. The salt does not evaporate, so the water in the container is fresh. This process is called water desalination.
Salt Water Distillation (Water Cycle)
- 1 quart warm water
- 2 tablespoons salt
- spoon for stirring
- bowl with a somewhat flat bottom
- small glass jar (ie baby food jar)
- duct tape
- clear plastic wrap
- small rock or weight
- Combine the water and salt to make saltwater. Stir with the spoon.
- Pour about 1 inch of saltwater into the bowl.
- Put the jar in the bowl. (The jar must be shorter than the bowl)
- Cover the bowl with plastic wrap.
- Use the duct tape to seal the plastic wrap on the bowl.
- Put a small rock or weight on the plastic wrap, just above the opening of the jar. This will cause the evaporated water to run down the plastic wrap into the jar.
- Put the still outside on a warm sunny day.
- Take off the plastic wrap and see the water collected in the jar.
- With an adult’s permission, taste the water you collected.
- Caution the student to never taste anything in an experiment without an adult’s permission.
- Does the water taste salty or fresh?
- What happens if you use juice in the bowl instead of saltwater? What ends up in the jar?