Question

How do you write a balanced chemical equation for the combination of octane, ${{C}_{8}}{{H}_{18}}$ with oxygen to obtain carbon dioxide and water?

Answer 1

To solve this type of question it is important to understand the reaction condition and the type of reaction. And the most important step is to balance the chemical reaction.

Complete answer:
The chemical reaction involved in the question is:
${{C}_{8}}{{H}_{18}}+{{O}_{2}}\to C{{O}_{2}}+{{H}_{2}}O$
Octane reacts with oxygen and produces carbon dioxide and water.
Now we have to check whether the reaction is balanced or not. So, here if we check there are 8 carbon atoms on the right-hand side and 1 carbon on the left-hand side of the reaction. Similarly, there are 18 hydrogens on the right-hand side and 2 hydrogen atoms on the left-hand side of the reaction respectively and 2 oxygen atoms on right-hand side and 3 oxygen atoms on the left-hand side of the reaction.
To balance carbon, we will multiply the carbon molecule on the right-hand side by 8. To balance hydrogen atoms, we will multiply the hydrogen molecule on the right-hand side by 9. Now when we find out that we have to multiply by fraction to balance the reaction then we can multiply the whole equation by integer.
The balanced chemical reaction is:
$2{{C}_{8}}{{H}_{18}}+25{{O}_{2}}\to 16C{{O}_{2}}+18{{H}_{2}}O$

Note:
Law of conservation of mass states that both the reactants and products have the same mass. And we know that in a chemical reaction mass can neither be created nor be destroyed. Initially we will check whether the given reactants and products are correct or not. There are coefficients which are used to balance the reaction. We should remember that the subscript near each element cannot be changed; we can only change the coefficients to balance the reaction.