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General Chemistry Principles, Patterns, and Applications, 2011

General Chemistry Principles, Patterns, and Applications, 2011

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Summary<br />

More than 80% of the energy used by modern society (about 3 × 10 17 kJ/yr) is from the combustion of<br />

fossil fuels. Because of their availability, ease of transport, <strong>and</strong> facile conversion to convenient fuels,<br />

natural gas <strong>and</strong> petroleum are currently the preferred fuels. Supplies of coal, a complex solid material<br />

derived from plants that lived long ago, are much greater, but the difficulty in transporting <strong>and</strong> burning a<br />

solid makes it less attractive as a fuel. Coal releases the smallest amount of energy per gram of any fossil<br />

fuel, <strong>and</strong> natural gas the greatest amount. The combustion of fossil fuels releases large amounts of<br />

CO2 that upset the balance of the carbon cycle <strong>and</strong> result in a steady increase in atmospheric CO2 levels.<br />

Because CO2 is agreenhouse gas, which absorbs heat before it can be radiated from Earth into space,<br />

CO2 in the atmosphere can result in increased surface temperatures (thegreenhouse effect). The<br />

temperature increases caused by increased CO2 levels because of human activities are, however,<br />

superimposed on much larger variations in Earth’s temperature that have produced phenomena such as<br />

the ice ages <strong>and</strong> are still poorly understood.<br />

K E Y T A K E A W A Y<br />

<br />

Thermochemical concepts can be used to calculate the efficiency of various forms of<br />

fuel, which can then be applied to environmental issues.<br />

C O N C E PTUAL P R OBLEMS<br />

1. Why is it preferable to convert coal to syngas before use rather than burning coal as a solid fuel?<br />

2. What is meant by the term greenhouse gases? List three greenhouse gases that have been implicated in<br />

global warming.<br />

3. Name three factors that determine the rate of planetary CO 2 uptake.<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

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