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Re: energy in the tank



this won't end the thread, but I must add:

Compare the "heat" obtained from burning gasoline and that obtained by
burning the same amount of H and C.

bc who taught Chem. one 1/4 and assigned the above as a problem using
methane. (The text included a table with, inter alia, those "heats" of
combustion. [n.b. quotation marks -:) ]

John Barrer wrote:

I think we should be VERY careful about referring to
energy stored in the gas tank. It reinforces the
faulty notion on the part of many students that
chemical bonds store energy. This is not true since
energy is released as bonds form; energy must be added
to a molecule to break bonds. The oxidation of
gasoline takes us to a lower potential well and energy
is released in the reaction, but it was not "stored"
in the gasoline.

I recently saw a paper which reported the results of
conceptual testing of Purdue (I believe) undergrad
science majors. A LARGE majority believed that
chemical bonds store energy. We should studiously
avoid reinforcing that misconception. Unless, of
course, one feels that this is not a significant
misconception. John Barrere

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