Question

What is the stoichiometric coefficient for oxygen when the following equation is balanced using the lowest, whole-number coefficients
________ C3H8O(l) + ________ O2(g) → ________ CO2(g) + ________ H2O(l)

5
3
9
7

I came up with 6 as the coefficient, but that is not an option?

Answer 1

first balance the carbons and the hydrogens

C3H8O(l) + O2(g) →3CO2(g) + 4H2O(l)

then you end up with 10 O's on the right

you have 1 O from the alcohol on the left, so you need 9

C3H8O(l) +\(\dfrac{9}{2}\) O2(g) →3CO2(g) + 4H2O(l)

you can't have fractions so multiply it through by 2

2 C3H8O(l) +9 O2(g) →6 CO2(g) + 8 H2O(l)