Oil as an Energy Source
Combustion of hydrocarbons is a burning process. The hydrocarbons are combined with oxygen and the resulting reaction produces water and carbon dioxide. The energy released during combustion can be estimated from the bond energies and the more hydrogen atoms per carbon atom in a hydrocarbon, the more energy will be released during combustion. Petroleum has a high content of saturated hydrocarbons; however, it can also contain a significant amount of other molecules. Crude oil contains 45.2kJ/mole, but gasoline contains 48.1 kJ/mole. Gasoline has fewer of these other molecules. 28
This is an important section, as we have come full circle with petroleum. Students can now use various sources of fuel in combustion reactions (pencil and paper) in order to make judgements about which types of fuels refined from petroleum are the most efficient. One again, mole-mole ratios and mole-mass conversions can be reinforced. When using bond energies to calculate which liquid fuel produces more energy upon combustion, it it important to remember that 1598 kJ is released in the formation of every mole of carbon dioxide produced in the combustion reaction.
From this point, the unit could delve into the detrimental effects of increasing carbon dioxide levels in the atmosphere. We will be doing a unit on gases after this unit. That unit incorporates levels of atmospheric carbon dioxide, hydrogen sulfide and other environmentally detrimental gases. It also includes ideas for cleansing the air, reducing pollution and comparing sources of energy.
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