This experiment tests the acidity, turbidity, ammonia content and nitrate content in water collected from a variety of locations. The teacher can decide to compare samples from upstream and downstream of an area in a water source where human activity takes place or from various water sources in the community. The acidity is tested with pH paper, the turbidity with a turbidity meter, and the ammonia content and nitrate content with a freshwater test kit.
This experiment is used to test the different levels of carbohydrates in low-fat milk, powdered milk and soy milk. It is performed by heating the same amount of each type of milk to 55 degrees C in beakers. Each milk sample is stirred while drops of acetic acid are added to the beaker until the solution turns clear and a mass of casein protein forms at the bottom of the beaker. The casein is then removed from each beaker and 4 grams of calcium carbonate are added to the liquid remaining in each beaker and stirred. Heat the solutions to a boil while stirring and proteins will precipitate. Use filtering paper to filter each solution into a different Erlenmeyer flask and continue until 25 ml of the solution remains. Add 100 ml of ethanol to the 25 ml in each Erlenmeyer flask. Collect the lactose crystals that form in each and use a digital weighing scale to find the weight of each amount of collected crystals. The milk with the lowest crystal weight has the lowest carbohydrate amount.
This experiment is conducted to measure the effectiveness of garlic in fighting bacteria by comparing the bacteria growth in three different specimens. In the first, test tube put 100 ml of milk; in the second, put 100 ml of milk and stir in a small amount of Escherichia coli using a toothpick; and in the third, put 100 ml of milk and use a toothpick to stir in a small amount of Escherichia coli and 5 ml of garlic extract made by grinding and juicing fresh garlic cloves. Make sure each test tube is properly stirred and allow them to incubate for 2 hours. Using a separate syringe for each test tube, remove 10 ml of each solution and apply each to a separate agar petri dish prepared with blood agar. Cover the petri dishes and place them in a cool shaded area. Use a ruler to measure the diameter of the bacteria colonies that grow in the petri dishes every day for the next five days.
This experiment is used to test how exposure to air over a period of time affects the amount of vitamin C in orange juice through the use of titration. On the first day, shake up a gallon bottle of orange juice, then measure 20 ml of orange juice into a 50 ml Ehrlenmeyer flask. Fill a 50 ml buret with 40 ml of iodine using a funnel. Place the flask below the buret. Slowly allow the iodine to drip from the buret into the flask. Swirl the flask around to mix the solution after every drop. Once the solution turns a dark blue-black color, the titration is complete. The amount of iodine necessary to complete the titration shows the amount of vitamin C in the orange juice. Place the orange juice back into the refrigerator without the cap or any covering over the mouth of the bottle. Repeat the test every day for a week to observe what happens to the amount of vitamin C over time.