This rock and soil experiment is designed to show how soil helps to balance and neutralize acidity in rain. Start by collecting a bucket of rainwater. If there's no rainwater in the area, add five tablespoons of vinegar to a gallon of water. Cut a liter soda bottle in half and place a coffee filter in the open base of the bottle. Collect soil and rock samples, packing them into the coffee filter. Test the PH of the rainwater prior to filtering it through the sediment. After getting your data with a basic PH kit, filter the water through the soil, measuring the PH of the water after going through the filter. The data should show a neutralization of acidity due to the soil and rock.
This experiment is designed to show your students which types of rocks are more basic than others, causing greater neutralization to occur. Place five different types of rocks on a table, making sure to place basic rocks such as limestone and marble on the table with other more common rocks. Pour a combination of lemon juice and water onto each rock. Have your students note which rocks have a greater reaction with the solution. The more basic rocks, such as limestone, should fizz and bubble.
In addition to literally neutralizing the acidity of the water/acid solution, basic rocks such as limestone also tend to have a higher porosity than regular rocks. While a typical rock has a porosity of one percent, limestone is closer to 15 percent, which means that it can literally absorb a portion of the solution in addition to neutralizing it. Pour a diluted acid/water mixture onto a variety of different rocks. After the liquid finishes reacting with the rock, pour pure water onto the rocks to see how much additional liquid the rock will absorb. The limestone will absorb more than the typical rock you find in your garden, leaving less water and residue around the rock.
This experiment is designed to show how a basic rock, such as limestone, can help neutralize water. Get two glass beakers, then pour water in one and vinegar in the other. Drop a piece of limestone in each, noting the differences between the two reactions. The limestone should interact with the vinegar, bubbling while also creating a layer of calcium acetate on the bottom of the cup. The water should be slightly absorbed by the limestone, but not interact with it in any drastic way.