Question

What coefficient would the `O_2` have after balancing `C_4H_8 + O_2 -> CO_2 + H_2O`?

Answer 1

the coefficient is 6

Explanation:

The balancement of the reaction requires the conservation of mass, each atom of carbon in `C_4H_8` consumes one `O_2` molecule, and every two atoms of hydrogen one oxygen atom is consumed.
So 4 molecules of `O_2` used by carbon add to 2 molecules of `O_2` used by hydrogen, in total 6 molecules of `O_2`
The balanced equation is:
`C_4H_8 + 6 O_2 rarr 4CO_2 + 4H_2O`