Associate Safety Professional Practice Exam

What mechanism describes the transfer of thermal energy from one molecule to another?

1. Convection

2. Conduction

3. Radiation

4. Diffusion

The correct answer is: Conduction

The transfer of thermal energy from one molecule to another is best described by conduction. This mechanism involves direct contact between molecules, where thermal energy is passed from the higher-energy (hotter) molecules to the lower-energy (cooler) ones through collisions and interactions at the atomic or molecular level. In conduction, heat flows through a material without any movement of the material itself; instead, the thermal energy simply moves through the bonds that hold the atoms or molecules together. It is the primary means of heat transfer in solids, especially metals, where closely packed atoms facilitate efficient energy transfer. Convection, on the other hand, relates to the transfer of heat through the movement of fluids (liquids or gases) where warmer areas expand and rise while cooler areas sink. Radiation involves the transfer of heat in the form of electromagnetic waves and does not require a medium to travel through. Diffusion refers to the movement of particles from an area of high concentration to an area of low concentration, which is more about the distribution of molecules than the transfer of thermal energy specifically. Thus, conduction accurately describes the process by which thermal energy is transferred from molecule to molecule.