Question

In the reaction C5H8 + ________ O2 ➡ 8H2O + HCO2, what coefficient should be placed in front of O2 to balance the reaction?

A. 5
B. 8
C. 9
D. No coefficient is needed

Answer 1

Further explanation

Equalization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:

• 1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c, etc.

• 2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index (subscript) between reactant and product

• 3. Select the coefficient of the substance with the most complex chemical formula equal to 1

For gas combustion reaction which is a reaction of hydrocarbons with oxygen produces CO₂ and H₂O (water vapor). can use steps:

Balancing C, H, and the last O

1. gives a coefficient

C₅H₈+aO₂ ⇒ 5CO₂ + 8H₂O

O⇒left =2a, right= 5.2+8=18 ⇒ 2a=18⇒a=9

So the coefficient in front of O₂ = 9

But this reaction is not balanced because the number of H is not balanced (8 on the left and 16 on the right, but if we use this equation:

C₅H₈ + 7O₂⇒ 5CO₂ + 4H₂O

then the reaction will be balanced