Here's how to balance the chemical equation for the combustion of methanol (CH3OH):

1. Write the unbalanced equation:

CH3OH + O2 → CO2 + H2O

2. Balance the carbon atoms:

There's one carbon atom on each side, so carbon is already balanced.

3. Balance the hydrogen atoms:

There are four hydrogen atoms on the left (CH3OH) and two on the right (H2O). Add a coefficient of 2 in front of H2O:

CH3OH + O2 → CO2 + 2H2O

4. Balance the oxygen atoms:

There are three oxygen atoms on the left (one in CH3OH and two in O2) and four on the right (two in CO2 and two in 2H2O). Add a coefficient of 3/2 in front of O2:

CH3OH + 3/2 O2 → CO2 + 2H2O

5. (Optional) Make coefficients whole numbers:

Multiply the entire equation by 2 to get whole number coefficients:

2CH3OH + 3O2 → 2CO2 + 4H2O

The balanced equation is:

2CH3OH + 3O2 → 2CO2 + 4H2O