Which of the following substances stores the most chemical energy per mole?

• A. Oxygen (O2)
• B. Water (H2O)
• C. Carbon dioxide (CO2)
• D. Glucose (C6H12O6)

Answer: (D)

Verified step by step guidance

1. Understand that chemical energy stored in a substance is related to the energy contained in its chemical bonds, which can be released during chemical reactions such as combustion or metabolism.
2. Recognize that molecules with more complex structures and more bonds, especially C-H and C-C bonds, generally store more chemical energy per mole compared to simpler molecules like O2, H2O, or CO2.
3. Compare the molecular formulas: O2 (diatomic oxygen), H2O (water), CO2 (carbon dioxide), and C6H12O6 (glucose). Notice that glucose has many more atoms and bonds, including multiple C-H and C-C bonds, which are high-energy bonds.
4. Recall that oxygen (O2) is often a reactant that helps release energy from other molecules, water (H2O) and carbon dioxide (CO2) are typically products of energy-releasing reactions and thus have lower stored chemical energy.
5. Conclude that glucose (C6H12O6), being a complex organic molecule with many high-energy bonds, stores the most chemical energy per mole among the given substances.