Balancing Chemical Equations

Dr. B. explains how to balance a combustion reaction for octane. The process involves analyzing the number of carbon, hydrogen, and oxygen atoms on both sides of the equation. Initially, carbon and hydrogen atoms are balanced by adjusting coefficients. Oxygen atoms are recalculated and balanced last. To achieve whole number coefficients, the entire equation is multiplied by two, resulting in a balanced chemical equation with coefficients 2, 25, 16, and 18.

What is the initial number of carbon atoms on the reactant side in the combustion reaction for octane?

• 12

• 10

• 8

• 6

How many hydrogen atoms are present on the reactant side before balancing?

• 18

• 22

• 16

• 20

What coefficient is placed in front of CO2 to balance the carbon atoms?

• 9

• 6

• 7

• 8

To balance the hydrogen atoms, what coefficient is used in front of H2O?

• 8

• 7

• 9

• 10

How many total oxygen atoms are needed on the product side after balancing carbon and hydrogen?

• 20

• 22

• 25

• 24

What is the coefficient for O2 to balance the oxygen atoms in the equation?

• 24.5

• 25

• 23

• 22.5

What are the final coefficients for the balanced equation?

• 4, 50, 32, 36

• 1, 12.5, 8, 9

• 2, 25, 16, 18

• 3, 37.5, 24, 27