5.12     understand that nitrogen oxides and sulfur dioxide are pollutant gases which contribute to acid rain, and describe the problems caused by acid rain.

Nitrogen oxides dissolve in water to form acids like nitric acid.  Sulfur dioxide dissolves to form sulfurous acid  (H2SO3) which can be oxidised by oxygen in air to sulfuric acid (H2SO4).

Acid rain upsets the pH in lakes, killing fish and other living things.  It also changes the pH of soils.

Acid rain kills plants, such as trees, whose chemistry is sensitive to pH levels. Acid rain corrodes buildings, particularly those made of limestone.

The picture shows a medieval gargoyle damaged by acid rain.