Investigating Acid Rain
Objective: The student will observe that all rainwater will show acidity due to the chemical union of water with carbon dioxide in the atmosphere.
Procedure: During a rainstorm place a clean enamelware pan in an open area and collect some rainwater. Transfer the water collected to a clean glass jar. Then place a small sample of the rainwater in a dish or saucer and dip one end of a strip of blue litmus paper into the sample near its edge. Examine the color of the wet end of the litmus paper. Also observe the wetted end of a strip of red litmus paper, similar applied to another edge of the sample. A red color will indicate the presence of an acid; a blue color will indicate a base.
Record your observation:
Samples of rainwater collected from areas where smoke, smog, and other air pollutants such as gases containing oxides of sulfur and nitrogen are also present show a proportionately higher acid concentration. The more gases present unite chemically with the water, the more acid the rain.