How do hydrocarbons behave in combustion reactions?

1 Answer
Feb 15, 2017

Hydrocarbons are combusted to carbon dioxide and water.


And this combustion process drives our industry, propels ours cars, lights our homes, cooks our dinner, and maintains our standard of living - it enables us to live beyond 30.

Methane gas is extensively used for power generation; its combustion reaction is a formal redox reaction in which #C(-IV)# in methane is oxidized to #C(+IV)# in carbon dioxide.

And I can simply represent this combustion reaction, if I can balance mass and charge. Typically, carbon is balanced as carbon dioxide, under conditions of complete combustion:

#CH_4(g) + 2O_2(g) rarr CO_2(g) + 2H_2O(l) + "energy"#

To balance these things you usually follow the order, balance the carbons as carbon dioxide, then balance the hydrogens as water, and then balance the oxygens by adding oxygen gas. Even numbered alkanes require a half-integral coefficient:

#H_3C-CH_3(g) + 7/2O_2(g) rarr 2CO_2(g) + 3H_2O#

Alternatively you could double the entire equation.

So the take home message: #"if it produces carbon dioxide, it's a"#
#"combustion reaction."# Carbon, as soot, and carbon monoxide, are the products of incomplete combustion. Capisce?