When a log burns, is any matter converted into heat and light energy?

The process of burning a log involves a chemical reaction known as combustion, where the wood reacts with oxygen in the air. During this reaction, the chemical bonds in the wood (which is primarily made up of carbon, hydrogen, and some oxygen) are broken down. This process releases energy in the form of heat and light.

However, it's important to note that while energy is released during combustion, the matter itself—the atoms and molecules that comprise the wood—are not converted into energy. Instead, they are transformed into different substances, primarily carbon dioxide and water vapor, through this reaction. The mass of the log before burning is equal to the mass of the resulting products plus any gases that are released into the atmosphere.

Thus, in the context of the question, matter is not converted into energy; rather, energy is released as the matter undergoes a transformation. Consequently, the statement that matter is converted into heat and light energy is inaccurate.