How does air pollution lead to acid rain?

1 Answer
Sep 16, 2015

Some factories and industries burn sulphur to release sulphur dioxide into the air. For example, during preparation for the contact process.
S+O_2->SO_2S+O2SO2
This sulphur dioxide then reacts with oxygen in the air to form sulphur trioxide.
2SO_2+O_2->2SO_32SO2+O22SO3
(During the contact process, which is the industrial preparation of sulphuric acid, this takes place at high temperature and pressure and in the presence of a Vanadium pentoxide catalyst.).

Both of these products can react with water in the atmosphere when it rains to form acid rain, sulphurous acid or sulphuric acid.

SO_2+H_2O->H_2SO_3SO2+H2OH2SO3

SO_3+H_2O->H_2SO_4SO3+H2OH2SO4

This acid rain can erode away metals etc.