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Physical
Thermochemistry
Safety
SI units were used where possible. Unless otherwise stated, standard conditions were used.
Sulfur dioxide (spelt in British English Sulphur dioxide) has the chemical formula SO2. The gas is irritant to the lungs and is frequently described as smelling of rotten eggs.
It is produced by volcanoes and in various industrial processes. In particular, poor-quality coal and petroleum contains sulfur compounds, and generate sulfur dioxide when burned: the gas reacts with water and atmospheric oxygen to form sulfurous acid (H2SO3) - and thus Acid rain.
Sulfur dioxide is sometimes used as a food additive, particularly as a preservative in alcoholic drinks.
The word equation for acid rain is:
sulfur dioxide + water -> hydrogen sulfite
H2SO3 is also called "hydrogen sulfite".