3.22 Combustion Reactions
FIGURE 3.32
The burning of charcoal is a combustion
reaction.Combustion of Hydrocarbons
The fuel that burns in a combustion reaction contains compounds called hydrocarbons. Hydrocarbons are compounds
that contain only carbon (C) and hydrogen (H). The charcoal pictured in theFigure3.32 consists of hydrocarbons.
So do fossil fuels such as natural gas. Natural gas is a fuel that is commonly used in home furnaces and gas stoves.
The main component of natural gas is the hydrocarbon called methane (CH 4 ). You can see a methane flame in the
Figure3.33. The combustion of methane is represented by the equation:
CH 4 + 2O 2 →CO 2 + 2H 2 O
FIGURE 3.33
The combustion of methane gas heats a
pot on a stove.Q:Sometimes the flame on a gas stove isn’t just blue but has some yellow or orange in it. Why might this occur?
A:If the flame isn’t just blue, the methane isn’t getting enough oxygen to burn completely, leaving some of the
carbon unburned. The flame will also not be as hot as a completely blue flame for the same reason.
You can simulate the combustion of hydrocarbons, including methane, at this URL: http://group.chem.iastate.edu/Gr
eenbowe/sections/projectfolder/flashfiles/stoichiometry/stoic_excess_oxy.html.