Demonstrating acid rain in the classroom is a valuable activity but while using carbon dioxide is fine, sulphur and nitrogen dioxides, two of the major contributors to acid rain, are highly toxic. In addition, nitrogen dioxide is most commonly prepared using copper turnings and concentrated nitric acid, a reagent to be avoided if it can be.
This experiment involves the preparation of very small quantities of the gases in situ in a corked test tube. samples of the gas are then removed by pasteur pipette and tested in universal indicator solution. The amount of gas released into the air is minimal and so the activity can be carried out by pupils in a well-ventilated laboratory.
