Editing Combustion (section)

===Stoichiometric combustion of a hydrocarbon in air===

If the stoichiometric combustion takes place using air as the oxygen source, the [[nitrogen]] present in the air ([[Atmosphere of Earth]]) can be added to the equation (although it does not react) to show the stoichiometric composition of the fuel in air and the composition of the resultant flue gas. Treating all non-oxygen components in air as nitrogen gives a 'nitrogen' to oxygen ratio of 3.77, i.e. (100% &minus; {{chem|O|2}}%) / {{chem|O|2}}% where {{chem|O|2}}% is 20.95% vol:
:<math chem="">\ce{C}_x \ce{H}_y + z\ce{O2} + 3.77z\ce{N2 ->} x\ce{CO2} + {y\over 2} \ce{H2O} + 3.77z\ce{N2}</math>
where <math>z = x + {y\over 4}</math>.

For example, the stoichiometric combustion of methane in air is:
:<math chem="">\ce{\underset{methane}{CH4} + 2O2} + 7.54\ce{N2-> CO2 + 2H2O} + 7.54\ce{N2}</math>

The stoichiometric composition of methane in air is 1 / (1 + 2 + 7.54) = 9.49% vol.

The stoichiometric combustion reaction for C{{sub|α}}H{{sub|β}}O{{sub|γ}} in air:
:<math chem>\ce{C_\mathit{\alpha}H_\mathit{\beta}O_\mathit{\gamma}} + \left ( \alpha + \frac{\beta}{4} -\frac{\gamma}{2} \right ) \left ( \ce{O_2} + 3.77 \ce{N_2} \right ) \longrightarrow \alpha \ce{CO_2} + \frac{\beta}{2} \ce{H_2O} + 3.77 \left ( \alpha + \frac{\beta}{4} -\frac{\gamma}{2} \right ) \ce{N_2}</math>

The stoichiometric combustion reaction for C{{sub|α}}H{{sub|β}}O{{sub|γ}}S{{sub|δ}}:

:<math chem>\ce{C_\mathit{\alpha}H_\mathit{\beta}O_\mathit{\gamma}S_\mathit{\delta}} + \left ( \alpha + \frac{\beta}{4} -\frac{\gamma}{2} + \delta \right ) \left ( \ce{O_2} + 3.77 \ce{N_2} \right ) \longrightarrow \alpha \ce{CO_2} + \frac{\beta}{2} \ce{H_2O} + \delta \ce{SO_2} + 3.77 \left ( \alpha + \frac{\beta}{4} -\frac{\gamma}{2} + \delta \right ) \ce{N_2}</math>

The stoichiometric combustion reaction for C{{sub|α}}H{{sub|β}}O{{sub|γ}}N{{sub|δ}}S{{sub|ε}}:

:<math chem>\ce{C_\mathit{\alpha}H_\mathit{\beta}O_\mathit{\gamma}N_\mathit{\delta}S_\mathit{\epsilon}} + \left ( \alpha + \frac{\beta}{4} -\frac{\gamma}{2} + \epsilon \right ) \left ( \ce{O_2} + 3.77 \ce{N_2} \right ) \longrightarrow \alpha \ce{CO_2} + \frac{\beta}{2} \ce{H_2O} + \epsilon \ce{SO_2} + \left ( 3.77 \left ( \alpha + \frac{\beta}{4} -\frac{\gamma}{2} + \epsilon \right ) + \frac{\delta}{2} \right ) \ce{N_2}</math>

The stoichiometric combustion reaction for C{{sub|α}}H{{sub|β}}O{{sub|γ}}F{{sub|δ}}:

:<math chem>\ce{C_\mathit{\alpha}H_\mathit{\beta}O_\mathit{\gamma}F_\mathit{\delta}} + \left ( \alpha + \frac{\beta-\delta}{4} -\frac{\gamma}{2} \right ) \left ( \ce{O_2} + 3.77 \ce{N_2} \right ) \longrightarrow \alpha \ce{CO_2} + \frac{\beta-\delta}{2} \ce{H_2O} + \delta \ce{HF} + 3.77 \left ( \alpha + \frac{\beta-\delta}{4} -\frac{\gamma}{2} \right ) \ce{N_2}</math>