Question

What is the balanced equation for the complete combustion of `"C"_2"H"_6"`?

Answer 1

Balanced Equation:

`"2C"_2"H"_6 + "7O"_2` `rarr` `"4CO"_2 + "6H"_2"O"`

Explanation:

General rules for balancing combustion equations:

1. Balance the carbons: If the alkane has an even number of carbon atoms, place a coefficient of 2 in front of its formula, then balance the carbons.
2. Balance the hydrogens.
3. Balance the oxygens.

Balance the carbons. Since the formula for the alkane `"C"_2"H"_6"` has an even number of carbon atoms, place a coefficient of `2` in front of its formula first. Next place a `4` in front of the `"CO"_2"`.

`color(red)("2")"C"_2"H"_6 + "O"_2` `rarr` `color(red)("4")"CO"_2 + "H"_2"O"`

Balance the hydrogens.
Place a `6` in front of the `"H"_2"O"`.

`"2C"_2"H"_6 + "O"_2` `rarr` `"4CO"_2 + color(red)("6")"H"_2"O"`

Balance the oxygens.
Place a `7` in front of the `"O"_2"`.

`"2C"_2"H"_6 + color(red)("7")"O"_2` `rarr` `"4CO"_2 + "6H"_2"O"`