Starting with the unbalanced equation for the combustion of ethanol, C2H5OH (l) + O2 (g) →CO2 (g) + ? H2O (l) what coefficient should be placed in front of H2O to balance the hydrogen atoms?

C2H5OH (l) + O2 (g) → CO2 (g) + ? H2O (l)

The coefficient should be 3

Explanation:

C2H5OH (l) + O2 (g) → CO2 (g) + ? H2O (l)

The chemical equation is a reaction between ethanol and oxygen. The reaction yield is carbon dioxide and water. Balancing the chemical equation requires one to make the number of atoms on the reactant side be equal to the number of atoms on the product side.

C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l)

The hydrogen atom on the left hand side of the equation is 6. Therefore, the number of atom of hydrogen should be 6 on the right hand side. The number of oxygen atom on the left hand side is 7. Therefore, the number of Oxygen atom on the right hand side should 7. Oxygen atom in carbon dioxide (right hand side) is 4 atoms, therefore, it requires 3 atoms of oxygen to make the oxygen atoms 7.

Using 3 as the coefficient of water in the equation will make hydrogen 6 and oxygen 3. Adding the 3 oxygen to the already 4 atoms of oxygen in carbon dioxide will make oxygen 7 atoms