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Name:  Phil
Status: educator
Grade: 9-12
Location:NY
Country: N/A
Date: 11/22/2005


Question:
Is there any difference between burning paraffin wax and soy wax? Our assumption is that complete combustion will produce carbon dioxide and water for both types and burning in air will produce all of the usual byproducts.


Replies:
Sure, complete (non-smoky) combustion will reduce both waxes to CO2 and H2O.

If you really mean complete combustion, the amounts of other byproducts should be very small for either wax. Then all that can change is the ratio of CO2 to H2O, the oxygen required per gram of fuel, and the heat released.

Differences are mainly that the soy wax probably has a different net composition than paraffin wax. Paraffin will have H and C atoms only, no O or N or S or P. And since the molecule is roughly H-(CH2)n-H, with n>20, the net composition is about CH2. Other waxes will have differences, such as occasional O's (ketone or hydroxyl or acid groups), which reduce the heat of combustion. They may also have unsaturations (C=C double-bonds) and rings, both of which can reduce the amount of H in the net formula by a small percentage.

If your burning is incomplete, these differences might change the amounts of any byproducts other than CO2 and H2O, much like the way oxygenated gasoline reduces the amount of NOx's produced in internal combustion engines. Ordinary candle-burning makes a little smoke and wax-fumes, so it might well be considered slightly incomplete. A soy wax flame might well have more or less smoke, and a different smoke-smell.

Jim Swenson



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