Simplifying Mole Ratios

Question

I was balancing and finding the mole ratio for octane to carbon dioxide in a combustion reaction of octane and it gave me 2:16, do I simplify it?

Answer 1

I would respectfully disagree with @Jesse E. because the question isn't "what is the ratio of octane to H2O or to some other molecule, but is asking the ratio to CO2.

2 C8H18 + 25 O2 ==> 16 CO2 + 18 H2O. So, the ratio of octane to CO2 is, indeed 2:16, but it is also 1:8 and that answer would be correct. In the example cited in the previous answer, it would still be ok to divide all coefficients by say, 3 to obtain A + 2/3B ==> 2C + 1/3D and calculate corresponding ratios. They would not all be whole number ratios, but who says that they have to be?

Answer 2

You can only simplify it the coefficients of the other molecules in the balanced equation can be simplified. For example, consider the hypothetical equation:

3A + 2B -> 6C + D

In this equation, the ratio of A to C is 3:6 but since the coefficients of molecules B and D can not be simplified, the ratio of A and C can not be simplified either. Hope this makes sense. if you have any questions, please feel free to contact me.