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Stoichiometric Combustion
For a methane/oxygen flame the chemical
reaction may be written:
CH4 + 2 O2 Þ
CO2 + 2 H2 O + Q
where Q is the heat
of combustion. In this reaction, atoms are conserved and the equation balances
for each of the species. The reaction is a stoichiometric reaction,
and the coefficients multiplying each of the chemical species are known as the
stoichiometric coefficients.
If air is used in the reaction rather than
pure oxygen, the inert gas nitrogen will be present. Air is about 79% nitrogen
by volume and 21% oxygen by volume. For a stoichiometric combustion reaction
in this case each mole of oxygen will be accompanied by 3.76 moles of
nitrogen. The reaction equation is then written:
CH4 + 2 O2 + 2(3.76 N2) Þ CO2 + 2 H2 O + 2(3.76 N2
) + Q
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