Page 19 - Curriculum Visions Dynamic Book

 Acid rain is responsible for damage to trees on already acid soils.
acid: compounds containing hydrogen which can attack and dissolve many substances. Acids are described as weak or strong, dilute or concentrated, mineral or organic.
strong acid: an acid that has completely dissociated (ionised) in water. Mineral acids are strong acids.
weak acid: an acid that has only partly dissociated (ionised) in water. Most organic acids are weak acids.
EQUATIONS: The reactions in the creation of acid rain Stage 1: Sulphur dioxide gas emissions created by burning sulphur-containing impurities in petroleum
Hydrogen sulphide + oxygen ➪ water + sulphur dioxide 2H2S(g) + 3O2(g) ➪ 2H2O(l) + 2SO2(g)
Sulphur
How sulphur dioxide in air makes acid rain
When sulphur dioxide dissolves in water the result is sulphurous acid. This is part of the environmental problem called acid rain (see page 22). But sulphur dioxide is also oxidised by oxygen in
the air to make sulphur trioxide. When sulphur trioxide dissolves in raindrops it produces the strong acid, sulphuric acid, which has a far more severe impact on the environment than the weak sulphurous acid.
Hydrogen
+➡+ Oxygen
Stage 3: Dissolving sulphur trioxide in raindrops
Sulphur trioxide + water ➪ sulphuric acid SO3(g) + H2O(l) ➪ H2SO4(aq)
+➡
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Stage 2: Creating sulphur trioxide
Sulphur dioxide + oxygen ➪ sulphur trioxide 2SO2(g) + O2(g) ➪ 2SO3(g)
+➡