Answer:
The coefficient of O2 when the equation is completely balanced is 19
Explanation:
The law of conservation of matter states that since no atom can be created or destroyed in a chemical reaction, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products.
Then, you must balance the chemical equation. For that, you must first look at the subscripts next to each atom to find the number of atoms in the equation. If the same atom appears in more than one molecule, you must add its amounts
Left side: 6 carbon, 14 hydrogen and 2 oxygen.
Right side: 1 carbon, 2 hydrogen and 3 oxygen.
The coefficients of each molecule below indicate the amount of each molecule for the reaction. This coefficient can be modified to balance the equation, just as you should never alter the subscripts.
By multiplying the coefficient mentioned by the subscript, you get the amount of each element present in the reaction. So, in this case you can see that in the reaction there is:
Left side: 2*6=12 carbon, 2*14=28 hydrogen and COEFFICIENT OF OXYGEN*2=? oxygen.
Right side: 12*1=12 carbon, 14*2=28 hydrogen and 12*2+14*1=38 oxygen.
As mentioned, you must have the same amount of each element on both sides. In this case, carbon and hydrogen have the same amount on both sides, so it only remains to balance the oxygen. For that, you must calculate the "OXYGEN COEFFICIENT" on the left side of the equation so that there are 38 oxygen atoms, just like the right side. This is expressed as:
COEFFICIENT OF OXYGEN*2=38
From the previous expression you can obtain:
COEFFICIENT OF OXYGEN=19
So, the coefficient of O2 when the equation is completely balanced is 19