Generally, the rain on the sky is neutral, but there is a kind of special acid rain – acid rain, floating into the eyes will sting people’s eyes, falling on the arm will be like a bug. Usually we use pH to indicate pH. The lower the pH, the stronger the acidity. We say that the rain with a pH of less than 5.6 is acid rain, and Chongqing has measured rainwater with a pH of 3.10. So how is acid rain formed? Why is there acid rain in the sky?
Acid rain is caused by air pollution. In production and life, people burn coal and oil, and the generated sulfur dioxide and nitrogen oxides enter the atmosphere, and after a combination of sunlight, water vapor and fly ash, a series of chemical reactions occur to form sulfuric acid, nitric acid or sulfate, and nitrate. The droplets, falling in the air, fall into the rain and snow, and become acid rain and acid snow.
At present, acid rain has been recognized as a global environmental pollution problem.