Answer
2 CH3OH + 3 O2 --> 2 CO2 + 4 H2O
$\Delta H = -1453 kJ $
Work Step by Step
CH3OH + 3/2 O2 --> CO2 + 2H2O
If we want to write this with whole number coefficients, we need to get rid of the 3/2. In order to do this, we multiply it by 2 to give 3, but then we need to multiply all of the other coefficients by 2 as follows:
2 CH3OH + 3 O2 --> 2 CO2 + 4 H2O .
Since we doubled the coefficients, we must also double the $\Delta H$ so that
$\Delta H $ = 2 * -726.5 kJ = -1453 kJ
