We Love to Travel:
Energy for Gasoline-powered Cars

For over a century, since the dawn of the automobile, Canadians have been in love with their cars. Assisted by a vast national network of highways, Canadians spend a major fraction of their "energy budget" on traveling by automobile.

Gasoline *

There are three reactions shown below, all representing the combustion of refined liquid petroleum, but each describing the process differently. For our purposes, the third (mass) equation is the most important.

Two molecular segments of a long chain hydrocarbon molecule, having (-CH2-) as a primary component, plus three molecules of oxygen will burn to produce two molecules of water, two molecules of carbon dioxide, and heat.


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Molecular equation

Word Equation

Mass equation

Carbon Dioxide


A specific gravity of 0.7 is used for gasoline.

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Refined liquid petroleum products such as gasoline, in which (-CH2-) is a common molecular component, is fairly simple and its combustion properties are easy to calculate.

These calculations characterize the combustion properties of conventional gasoline, home heating oil and diesel fuel.

Since we normally purchase gasoline by the litre it is useful to convert kilograms into litres. To convert kilograms of fuel to litres of gasoline the specific gravity of 0.7 was used.

The graph to the left shows the relationship between the volume of gasoline burned (in litres) and the mass of carbon dioxide produced (in kilograms).

Activity

Answer Key

* Footnote: Fossil fuels are a complex blend of hundreds of kinds of hydrocarbon molecules. The molecule in this example is one of the most abundant in the fuel being described, and as such, represents a good approximation of the entire combustion process for all fuels made of (-CH2-) segments.

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