Final answer:
None of the substances in the chemical equation CO + H2O → C7H16 are elements; they are all compounds. Chemical equations, especially those involving combustion of hydrocarbons, must be carefully balanced, considering all atoms, including any oxygen within the fuel molecules.
Step-by-step explanation:
The chemical equation CO + H2O → C7H16 represents a reaction producing fuel, and you asked which substance in this equation is classified as an element. Substance A) CO (Carbon Monoxide) is a compound of carbon and oxygen, B) H2O (Water) is a compound of hydrogen and oxygen, and C) C7H16 (Heptane) is a hydrocarbon, and therefore also a compound. Therefore, D) None of the substances are elements, as they are all compounds consisting of two or more different elements chemically combined.
Balancing chemical equations is crucial for understanding the stoichiometry of a reaction. When balancing equations involving combustion of hydrocarbons, the products are typically carbon dioxide and water. Many types of fuels, such as ethanol or methanol, contain oxygen atoms which must be taken into account in the balancing process.