In this experiment, your students will bring in two samples of water from home. One sample will be for testing, the other to allow their peers to taste the water. Using test strips or a pH meter, students will test for the relative alkalinity or acidity of their water and record the result. Students place a drop of soap solution in a 5 ml water sample and shake with a shaking machine for 15 seconds. They measure the suds. The more suds, the softer the water. Have your students taste each other's water and see if they can tell a difference or guess the pH or hardness after tasting.
Your students will study airborne acidity for a week or more. Identical selections of metals are placed in three air-tight containers, such as transparent sandwich boxes. One container will contain a beaker of water to produce a moist environment, the second silica gel to dry the air, and the third will contain a solution that releases sulfur dioxide gas. The class can be broken into small groups, each with its own set of boxes, or the class could observe the experiment as a whole. Students observe the corrosion over time, and you can ask them how they might stop the corrosion. In stage two, replicate the conditions, but ask students to experiment with methods of corrosion control.
In this experiment, your students will test the browning of apple slices in the open air compared with the browning of slices coated with lemon juice. Have each group cut a fresh slice of apple and place it on a tray. Your students will record observations every minute or so. After five minutes, have students peel the skin to compare. Then, take two apple slices and coat one with lemon juice. Compare the two slices over the next five minutes, peeling the skin off each for a final analysis.
Your students will see how chemicals are spread through diffusion in water. Each lab group will have a petri dish, a lead nitrate crystal and a potassium iodide crystal. The dishes will be filled with deionized water, and students will use forceps to place the crystals at opposite sides of their dish. As the crystals dissolve, they diffuse through the water, with the lead moving slower owing to its heavier mass. When they meet, lead iodide and potassium nitrate are created. The lead iodide creates a yellow cloud to demonstrate the reaction.