Octane (c8h18 ) reacts with oxygen (o2) to form carbon dioxide (co2) and water (h2o). when the equation below is balanced, the coefficient of octane is: c8h18 + o2 → co2 + h2o

                                2 C₈H₁₈  +  25 O₂    →   16 CO₂  +  18 H₂O

Solution:

Step 1: Write down the unbalanced chemical equation,

                                         C₈H₁₈  +  O₂    →    CO₂  +  H₂O

Step 2: Balance the Carbon atoms as,

As there are 8 carbon atoms in octane, therefore we will multiply CO₂ by 8 in order to balance it i.e.

                                         C₈H₁₈  +  O₂    →    8 CO₂  +  H₂O

Step 3: Balance the Hydrogen atoms;

                                         C₈H₁₈  +  O₂    →   8 CO₂  +  9 H₂O

Step 4: Balance the Oxygen atoms as,

                                         C₈H₁₈  +  12.5 O₂    →   8 CO₂  +  9 H₂O

Step 5: Multiply last equation by 2 in order to remove fractions as,

                                        2 C₈H₁₈  +  25 O₂    →   16 CO₂  +  18 H₂O