Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 104. Not illustrated. Chapters: Carbon Dioxide, Cantharidin, Acetic Anhydride, Phosphorus Pentoxide, Sulfur Trioxide, Dinitrogen Pentoxide, Phthalic Anhydride, Acid Anhydride, Dinitrogen Trioxide, Maleic Anhydride, Mellitic Anhydride, Ethylenetetracarboxylic Dianhydride, Sultone, Trifluoromethanesulfonic Anhydride, Propionic Anhydride, Dioxane Tetraketone, Malonic Anhydride, Trifluoroacetic Anhydride, Oxalic Anhydride, Succinic Anhydride, 3-Chlorophthalic Anhydride, Dodecenyl Succinic Anhydride, 4-Chlorophthalic Anhydride. Excerpt: -78 C, 194.7 K, -109 F (subl.) Carbon dioxide (chemical formula CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state. CO2 is a trace gas comprising 0.039% of the atmosphere. Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks. As of April 2010, carbon dioxide in the Earth's atmosphere is at a concentration of 391 ppm by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemispher...