What happens in a combustion reaction?

1 Answer
anor277
Jul 27, 2018

A material, a fuel, is oxidized by dioxygen gas....

Explanation:

And typically an hydrocarbon fuel is completely combusted to give carbon dioxide and water...and ENERGY....

As we examples, we consider the COMPLETE combustion of propane, and butane gases. The usual rigmarole is balance the carbons, as carbon dioxide....

#(i)# #underbrace(C_3H_8+O_2 rarr 3CO_2 + H_2O)_"UNBALANCED"#

Then balance the hydrogens, as water..........

#(ii)# #underbrace(C_3H_8+O_2 rarr 3CO_2 + 4H_2O)_"UNBALANCED"#

Then, finally, balance the oxygens....

#(iii)# #underbrace(C_3H_8+5O_2 rarr 3CO_2 + 4H_2O)_"BALANCED"#

With even-numbered alkanes, to achieve stoichiometric equivalence you have to either double the entire equation, or use a a half-integral coefficient, i.e. for butane.....

#C_4H_10(g) + 13/2O_2(g) rarr 4CO_2(g) + 5H_2O(l)#

#2C_4H_10(g) + 13O_2(g) rarr 8CO_2(g) + 10H_2O(l)#

Would energy be released or absorbed in these reactions? Why?

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