Example H.1

JD Malana
Posts: 21
Joined: Wed Nov 16, 2016 3:02 am

Example H.1

In the third step of balancing the equation for the combustion of C6H14 + O2 > CO2 + H2O,
the final balanced equation is C6H14 + 19/2 O2 > 6 CO2 + 7 H2O...
Why/how is the fractional coefficient used for O2 19/2?
Is there a specific method/formula for determining what fractions to use?

Sarah_Wilen
Posts: 62
Joined: Fri Jun 23, 2017 11:39 am
Been upvoted: 4 times

Re: Example H.1

To determine what fraction you need, what I would do is count up the oxygens (I need 19). 19 doesn't divide evenly, which is a problem because we have O2. So, I will do 19/2 because I know I need 19 Oxygens and I will "split" up the O2 to get 19 of them. In the end, I just multiply everything by 2 to cancel out the fraction.

A general rule for fractions I think would be, if there is a diatomic element, but you need an uneven number, you just see the number of that element you need and put it over 2.

Abby Ellstrom 1I
Posts: 53
Joined: Fri Sep 29, 2017 7:04 am

Re: Example H.1

Allowing for an improper fraction in your balanced equation makes it easier when initially balancing the equation so you don't have to do it in your head. However, a final balanced reaction should contain no fraction stoichiometric coefficients so simply multiply the entire equation by the denominator for your final answer.