Final answer:
The thermal energy from a toaster is transformed into chemical energy during the toasting process. The correct description is that the energy is converted, not destroyed, in accordance with the principles of thermochemistry and the second law of thermodynamics.
Step-by-step explanation:
When heat is transferred from a toaster to bread, the correct statement would be: Thermal energy used to toast the bread changes to chemical energy. This process is known as thermochemistry, which is a branch of chemistry that deals with the energy changes occurring during chemical reactions and state changes. As the bread receives thermal energy from the toaster, it undergoes a chemical reaction known as the Maillard reaction, which not only warms the bread but also creates new flavors and colors. Hence, the thermal energy does not get destroyed; it simply transforms into another form of energy - chemical energy in this case.
The second law of thermodynamics states that energy transfers are not completely efficient, meaning some energy is invariably lost as heat to the environment. In the case of toasting bread, while most of the thermal energy is used to toast the bread through the Maillard reaction, some is inevitably lost to the surrounding air and toaster parts as heat, not in terms of being destroyed, but rather dispersed in a way that is no longer useful for the process of toasting.