what are some useful chemical reactions?
['Synthesis of ammonia.', 'Combustion of hydrogen / Electrolysis of water.', 'Combustion of methane (hydrocarbons)', 'Photosynthesis.', 'Synthesis of sulfuric acid.', 'Equilibrium of carbonic acid and carbon dioxide gas.', 'Biological formation of calcium carbonate.', 'Rusting of iron.']