Which of the following is typically the initial source of chemical energy in most chemical reactions?

• A. The heat released during the reaction
• B. The energy from external light sources
• C. The bonds between atoms in reactant molecules
• D. The energy stored in the products

Answer: (C)

Verified step by step guidance

1. Understand that chemical energy in reactions primarily comes from the breaking and forming of chemical bonds within molecules.
2. Recognize that the bonds between atoms in reactant molecules contain stored potential energy, which can be released or absorbed during a reaction.
3. Note that while heat or light can influence reactions, they are not the initial source of chemical energy; rather, they may provide activation energy or be a product of the reaction.
4. Identify that the energy stored in the products is the result of the reaction, not the initial source.
5. Conclude that the bonds between atoms in reactant molecules are typically the initial source of chemical energy in most chemical reactions.