How does nitric and sulfuric acid lead to acid rain?

Answer 1

Rather than nitric and sulphuric acid, its actually the gases nitrogen dioxide and sulphur dioxide that cause acid rain. These gases may originate from pure nitrogen or sulphur which reacts with oxygen (O2) in the atmosphere. The smelting process of metal sulphides (e.g. CuS) will also produce SO2. These gases can be produced via various methods so here are just some basic ones from the HSC syllabus.

Formation of Nitrogen Dioxide:

N2 + O2 -> 2NO

2NO + O2 -> 2NO2

Formation of Sulphur Dioxide:

S + O2 -> SO2

2CuS + 3O2 -> 2CuO + 2SO2

Nitric and sulphuric acid are the by-products of reacting these gases and moisture (H2O) in the atmosphere and give acid rain its acidic properties.

2NO2 + H2O -> HNO2 + HNO3 (remember that nitrous acid is also a product in this otherwise it will never balance)

SO2 + H2O + O2 -> H2SO4

Do note that nitric and sulphuric acid are components of acid rain and that acid rain is a mixture. Likewise, acid rain is not necessarily nitric or sulphuric acid. (Just a little note seeing as the wiki answers board frequently asks if either components are acid rain.)

Hope this helps :)