Chemical Concentrations

• Paper (to record your findings)
• Scissors
• Bleach
• Cotton
• Clock

• 2-gal. (8L) jug of water
• 2-liter plastic bottles
• Alum (a spice found in most supermarkets)

• 5 cups (600 mL) of soil
• Funnels
• Fine gravel

1. Use the funnel to pour about 1.4 L of dirty water into the 2-Liter plastic bottle with cap. The dirty water can be made by adding five cups of soil to two gallons of water. Describe the appearance of the water on paper.
    
2. Put the cap on the bottle and shake for about 30 seconds. Continue the process by pouring the water back and forth between two bottles 10 times. Record what part of the treatment process this action represents.
    
3. Pour the water from step two into a 2-liter bottle with the top cut off. Add two tablespoons of alum to the water. Stir the mixture slowly for about five minutes. What process is occurring?
    
4. Allow the water to stand undisturbed for 20 minutes. Observe the water at five-minute intervals and record your observations. What process is occurring here?
    
5. Cut the bottom from another 2-liter or 3-liter bottle. Construct a filter using cotton and the cheesecloth and plug the neck of the bottle with the filters. Secure with a rubber band.
    
6. Pour the fine sand over the cotton plug followed by activated charcoal, coarse sand, fine gravel and coarse gravel. Clean the filter by slowly pouring through 4-8 liters of clean tap water.
    
7. Place the filter over the bottom part of another bottle. Without disturbing the sediment in the container with the alum, pour the top two-thirds of the water through the filter. What process is occurring?
    
8. After waiting until more than half of the water poured through the filter has been collected, add two tablespoons of bleach to the filtered water. What part of the treatment process does the addition of bleach represent?
    
9. Record the differences in appearance and odor. Examine both treated and untreated water with a microscope and record your observations.
    
10. Write a brief report explaining how a water treatment facility purifies water for drinking. Check out our interactive version of the water treatment process.