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Seashore Resource |
Intro | 1.Field
Trip | 2.Rocky Shore | 3.Plankton |
5. Experiment.
Making fresh water from salt waterImagine you are marooned on a desert island, surrounded by seawater.
Unless you find some fresh water you will die of thirst!
Try the experiment below to make fresh water to save your life.
The things you will need to make fresh water from salt water:
a bucket
a glass jar (or cup)
2 stones
plastic lunch wrap
sticky tape or string
sea water or salty water ( you can make this by adding salt to water)
Set up your experiment as the drawing shows and put the bucket in the sun. Next day take off the plastic cover and look inside. The jar has water in it. Taste it – it’s fresh!
How does this work?
The sun has warmed the salt water making some of it turn into vapour (or steam). The
vapour rises up to the plastic cover where it cools and turns back into water again. The
drops of water run down the plastic to the stone weight and drip off into the jar. Only
the water evaporates, the salt is left in the salty water. This useful trick also works in
the desert, using plastic over a hole in the sand instead of over a bucket of sea water.
