Here's how to balance the chemical equation for the combustion of ethanol (C2H5OH) with oxygen (O2):

1. Write the unbalanced equation:

C2H5OH + O2 → CO2 + H2O

2. Balance the carbon atoms:

There are 2 carbon atoms on the left side (C2H5OH) and 1 on the right (CO2). To balance, put a 2 in front of CO2:

C2H5OH + O2 → 2CO2 + H2O

3. Balance the hydrogen atoms:

There are 6 hydrogen atoms on the left side (C2H5OH) and 2 on the right (H2O). Put a 3 in front of H2O:

C2H5OH + O2 → 2CO2 + 3H2O

4. Balance the oxygen atoms:

There are 3 oxygen atoms on the left side (O2) and 7 on the right (2CO2 + 3H2O). To balance, put a 3 in front of O2:

C2H5OH + 3O2 → 2CO2 + 3H2O

The balanced equation is:

C2H5OH + 3O2 → 2CO2 + 3H2O

Explanation:

This equation represents the complete combustion of ethanol. This means that ethanol reacts with oxygen to produce carbon dioxide and water. Balancing the equation ensures that the number of atoms of each element on both sides of the equation is equal, following the law of conservation of mass.