Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter. Societies at all levels of development could not function without the energy released by chemical reactions. In 2019, about 80% of US energy consumption came from the combustion of fossil carbon energy sources, 8% from nuclear reactions, and 11% from renewable sources. We use this energy for residential energy (16%); to transport food, raw materials, manufactured goods, and people (37%); for industrial production (35%); and for commercial facilities (12%).1 While these energy systems help us meet our essential needs, combustion of the fossil fuel sources are the primary contributor to global anthropogenic climate change.
Useful forms of energy are also available from a variety of chemical reactions other than combustion. For example, the energy produced by the batteries in a cell phone, car, or flashlight results from chemical reactions. This chapter introduces many of the basic ideas necessary to explore the relationships between chemical changes and energy, with a focus on thermal energy.
- US Energy Information Administration, Total Energy, Annual Energy Review, https://www.eia.gov/totalenergy/data/annual/ Data derived from US Energy Information Administration (August 2020).
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