Question
Below is the symbol equation for the combustion of octane with oxygen to produce carbon dioxide and water. What number is needed in the blank before O_(2) to balance the equation? C_(8)H_(18)+ldots O_(2)arrow 16CO_(2)+18H_(2)O
Answer
4
(209 Votes)
Georgia
Professional · Tutor for 6 years
Answer
25
Explanation
## Step 1: Firstly, inspect the unbalanced equation,
## Step 2:As per the Law of Conservation of Mass, the number of atoms should be same on both the reactant and product sides. The number of carbon and hydrogen atoms are the same on both sides of the equation. However, the oxygen atoms are not balanced.## Step 3:On the right side, calculate the total number of oxygen atoms:It can be obtained from two compounds,
and
.In
, each molecule of
contributes 2 oxygen atoms. So a total of
atoms from
.In
, each molecule of
contributes 1 oxygen atoms. So a total of
atoms from
. So in total, the right side of the equation has
oxygen atoms.## Step 4:Going to the left side, remember that in a molecule of
, there are 2 oxygen atoms. Therefore, to balance the equation with
oxygen atoms on the right side, we would require
molecules of
. ## Step 5:So, enter
as the coefficient in front of
to balance the equation. The balanced equation is thus:
.