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I am doing a science experiment on the energy output of some different fuels. I am going to be burning small amounts of fuel in a closed chamber and then measuring the heat generated, and the pollutants generated. I am going to filter the air for soot and unburnt hydrocarbons, and use a thermometer for measuring heat, but I want to know what products are produced from the burning of the fuels. I need help finding out the chemical formulas for burning these fuels with air (not pure O2, just air). I managed to find out the formula for methanol, but am having trouble with the rest.

The fuels I am thinking of testing are:

Diesel fuel

If you know of any web sites that might help me find this information, or know the formulas yourself, I would appreciate it if you could inform me. Also, if you know of where I could find some thermal testing instruments, I would like to know. Thank you for your help!
Question Date: 2006-02-17
Answer 1:

From your question, I am assuming that youre asking what the chemical formulas are for the different fuels that youre interested in studying. First, methanol is simply CH3OH, and if youre interested, ethanol is C2H5OH. Both are generally referred to as alcohols. Gasoline, kerosene, and diesel fuel are made up of aliphatic hydrocarbons, or molecules that are composed of only carbon and hydrogen. As it turns out, these types of fuels dont have a specific chemical formula, but rather are made up of several different types of hydrocarbons. Gasoline, for example, is mostly octane (C8H18), but is still comprised of five or six different types of hydrocarbons. Kerosene is made up of the next heavier fuel oils, and diesel fuel is even heavier yet.

When all of these fuels are burned in air, the hydrocarbons nominally react only with the oxygen in the air to from carbon dioxide and water. However some oxides of nitrogen can be formed (although not all that much). Also, there are also trace amounts of impurities (e.g. sulfur) in the fuel that can lead to other by-products. Also, due to the imperfect nature of burning these fuels, there is also some generation of carbon monoxide instead of carbon dioxide. The formation of carbon monoxide and sulfur-based pollutants is a big issue for engine emissions.

Here are a couple of links that describe in more detail how gasoline and other fuels are made.

how stuff works
more about

This link has a table contrasting the different amounts of energy from different types of fuels.

Measuring the heat released in chemical reactions is typically done in a calorimeter. As for the equipment, I would highly recommend that you talk to your parents and your science teacher about safety before beginning any experiments. Unfortunately, Im not too familiar with commercial sources of calorimeters and how much they would cost.
Hope this helps.

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