EXPERIMENT I - Water Purification Through Water Cycle

Everyone must familiar with the water cycle (technically known as the hydrological cycle), do you know what can it do to help us from its continuous movement of water over, above, and beneath the Earth's surface. As water moves around in the hydrosphere, it changes state among liquid, vapour, and ice. During the process through which a liquid becomes a vapor, it is defined as Evaporation. Minerals like salt and other substances dissolved in water are left behind. As a result, when the water vapor condenses to become water again, it is relatively pure. The evaporation and condensation are the key terms that help water purifying. While these process occurs during the water cycle, it can also be used to purify water for drinking or industry use.

Here, a simple experiment that you can do at home, it will help you understand how the water cycle helps to purify water.

MATERIALS NEEDED:

• 4 cups of dirt or sand a dozen stones,
• 2 quarts of water a large glass bowl with tall sides (mixing bowl),
• A short glass,
• Clear plastic wrap, and
• A sunny day.

PROCEDURE:

Mix the dirt (or sand) and water in a large bowl. Stand a clean and empty short glass in the center of the bowl. Place the bowl outside in the sun. Cover the bowl with the plastic wrap and weigh down the edges with the remaining rocks. Place one rock on the plastic wrap directly over the cup. Allow the bowl to remain in the sun for several hours. Look in the cup (it should contain some relatively clean water free of mud). Look in the bowl (it should contain the dried dirt).

VARIATIONS:

Add food coloring to water to demonstrate that this process does not remove all pollutants. This may be done simultaneously with the procedure above.

Source: Enviromental Protection Agency