Question

Which of the following is the correctly balanced equation for the incomplete combustion of heptene, C7H14? Please explain how you got the answer.
2C7H14+ 21O2→ 14CO2+ 14H2O

C7H14+ O2→ C7O2+ 7H2

C7H14+ 7O2→ 7CO + 7H2O

C7H14+ 14O → 7CO + 7H2O

Answer 1

Answer: C₇H₁₄ + 7O₂ → 7CO + 7H₂O

Explanation:

• For any equation to be balanced the number of (C, H, and O) atoms in the reactants side should be the same in the products side.

• The first choice is wrong because it is unbalanced equation that the reactants side has 22 O atoms and in the products side there is 14 O atoms.

• The second choice is wrong because the incomplete combustion of heptene results CO and/or CO₂ and H₂O.

• The third choice is the right answer that it has 7 atoms of C, 14 atoms of H, and 14 atoms of O in both reactants and products sides.

• The fourth choice is wrong because the combustion of heptene occurs in O₂ not in O.

Answer 2

Answer : The correct balanced equation will be,

$C_7H_{14}+7O_2\rightarrow 7CO+7H_2O$

Explanation :

Balanced chemical equation : It is the number of atoms of individual elements present on reactant side must be equal to the number of atoms of individual elements present on product side.

As we know that the hydrocarbons can undergo complete or incomplete combustion that depends on the amount of oxygen available.

Complete combustion : It takes place when there is a good supply of oxygen. In this, hydrocarbon react with the oxygen to give carbon dioxide and water as a product.

Incomplete combustion : It takes place when there is a poor supply of oxygen. In this, hydrocarbon react with the oxygen to give carbon monoxide, carbon and water as a product.

As per question, the incomplete combustion of heptene react with oxygen to give carbon monoxide and water as a product.

Therefore, the balanced chemical reaction will be :

$C_7H_{14}+7O_2\rightarrow 7CO+7H_2O$