Question

How would you balance this equation: `C_2H_6+O_2 -> CO_2+H_2O`?

Answer 1

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

Explanation:

`"C"_2"H"_6" + O"_2` `rarr` `"CO"_2" + H"_2"O"`

Balance H first.

There are 6 H atoms on the left and 2 on the right. Place a coefficient of 3 in front of the `"H"_2"O"`.

`"C"_2"H"_6" + O"_2` `rarr` `"CO"_2" + 3H"_2"O"`

Balance C next.

There are 2 C atoms on the left and 1 C atom on the right. Add a coefficient of 2 in front of the `"CO"_2"`.

`"C"_2"H"_6" + O"_2` `rarr` `"2CO"_2" + 3H"_2"O"`

Balance O last.

There are 2 O atoms on the left and 7 O atoms on the right.

Place a coefficient of 7/2 in front of `"O"_2"` on the left.

`"C"_2"H"_6" + "7/2"O"_2` `rarr` `"2CO"_2" + 3H"_2"O"`

All of the coefficients in a chemical equation must be whole numbers. To change `7/2` to a whole number, multiply all coefficients times 2.

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

There are now 4 C atoms on both sides, 12 H atoms on both sides, and 14 O atoms on both sides. The equation is balanced.