# Question #189dd

Oct 2, 2015

${\text{C"_3"H"_8"S" + 6"O"_2 -> 3"CO"_2 + 4"H"_2"O" + "SO}}_{2}$

#### Explanation:

Start by predicting what the products of the reaction could be.

As its name suggests, propanethiol is a thiol, which implies that it contains a sulfohydryl group, $\text{-SH}$, bonded to a carbon atom.

More specifically, to get propanethiol, you repalce one hydrogen atom on a propane moelcule, ${\text{C"_3"H}}_{8}$, with a $\text{-SH}$ group. The molecular formula of the compound will thus be $\text{C"_3"H"_8"S}$.

This implies that the products of its combustion will no longer be exclusively carbon dixoide and water, like you get for hydrocarbons.

Instead, the reaction will also produce an oxide of sulfur, most likely sulfur dioxide, ${\text{SO}}_{2}$.

The unbalanced chemical equation will thus be

${\text{C"_3"H"_8"S" + "O"_2 -> "CO"_2 + "H"_2"O" + "SO}}_{2}$

Balance the carbon atoms first.

${\text{C"_color(red)(3)"H"_8"S" + "O"_2 -> color(red)(3)"CO"_2 + "H"_2"O" + "SO}}_{2}$

Balance the hydrogen atoms next.

${\text{C"_color(red)(3)"H"_color(green)(8)"S" + "O"_2 -> color(red)(3)"CO"_2 + color(green)(4)"H"_2"O" + "SO}}_{2}$

Finally, balance the oxygen atoms.

${\text{C"_color(red)(3)"H"_color(green)(8)"S" + 6"O"_2 -> color(red)(3)"CO"_2 + color(green)(4)"H"_2"O" + "SO}}_{2}$

And there you have it - the balanced equation for the combustion of propanethiol.