Salty water such as seawater is usually considered not drinkable. The process of removing salt and other non-volatile impurities from salt water is called distillation. A solar water purifier uses the greenhouse effect to trap energy from the sun. The mechanism of solar water purifier also demonstrates the water cycle that naturally occurs on earth: evaporation, condensation and precipitation.
Materials you will need:- A big bowl
- A plastic cup which is 1’’ shorter than sides of the bowl
- Clear plastic wrap
- Tape or rubber band large enough to go around the bowl
- Small rock or weight
- Salty water
Step-by-step instruction:
- Put salty water in the bowl.
- Place the plastic cup (with no water inside) in the center of the bowl.
- Cover the bowl with plastic wrap and use either tape or rubber band to secure the plastic wrap. Make sure the plastics warp is tight.
- Put the small rock or weight in the center of the plastic wrap. The extra weight in the center will ensure that the evaporated water will drop into the cup.
- Place the bowl under the sun and observe how distilled water start to accumulate inside the plastic cup for every hour or so.
- When there is enough water in the plastic up, open the plastic wrap and taste your purified water.
- Can you tell whether the water taste differently from tap water? If so, can you explain why?
