How to Use Salt Water to Purify Water
Salt water is frequently purified so that it can be used as drinking water. The process of removing salt from water is known as desalination and is performed on an industrial scale, especially in the Middle East. In this process, the water is evaporated into steam and the salt remains a solid. The steam is then collected and condensed back into a liquid without the salt. You can demonstrate this process at home by using passive heating to evaporate the water.
Things You'll Need
- Bucket or other container to mix salt water in
- One quart water
- Three tablespoons salt
- Large bowl
- Small glass tumbler or drinking glass
- Plastic wrap
- Rubber band
- Marbles
Instructions
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1
Make the salt water. Mix the salt and water thoroughly so that the salt is completely dissolved.
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2
Place the glass tumbler or drinking glass in the middle of the bowl at the deepest part of the bowl. The glass should not be plastic or paper because you don't want it to float once it's in the salt water.
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3
Pour enough salt water into the bowl so that the surface of the water ends up well below the top of the tumbler. Make sure no salt water gets poured into the tumbler.
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4
Place a piece of plastic wrap loosely over the bowl the bowl. Push down slightly in the middle of the wrap so that there is some slack in the wrap. Fold the plastic wrap over the edges of the bowl.
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5
Push a rubber band around the rim of the bowl over the plastic wrap so that a water tight seal between the plastic wrap and bowl is formed.
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Put a few weights such as marbles or pebbles on top of the wrap in the middle of the bowl. Ensure that the lowest point of the sag is directly above the cup and that the plastic wrap doesn't drop below the top of the cup.
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Move the bowl to a warm place and in direct sunlight. The water in the bowl will slowly evaporate from the heat and collect on the plastic, since it can't escape the bowl. The slope of the plastic wrap will cause the water droplets to slide down the plastic wrap to its lowest point. Eventually, the water will drip into the cup as it accumulates on the plastic wrap. The water in the cup will be pure, because the salt doesn't evaporate.
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