Burning fossil fuels releases carbon dioxide, CO2(g), which contributes to the greenhouse effect and hence to climate change. Burning some fossil fuels also releases nitrogen oxides and sulfur dioxides. These gases react with moisture in the air to produce acid precipitation: rain or snow containing dilute nitric acid and sulfuric acid. Precipitation is naturally acidic with a pH of 5.6 because carbon dioxide reacts with water to form carbonic acid. Precipitation is defined as being acidic if its pH is less than 5.6. Acid precipitation has many effects on the environment.
In aquatic ecosystems, the pH of surface water naturally ranges from 6 (slightly acidic) to 9 (slightly basic) depending on the biological activity and mineral content of rocks and sediment.
In this demonstration, students will compare the effects of acid on a number of objects to the effects of water. The beaker containing acid is a model of an environment exposed to acid precipitation.