What happens to matter in a log when it burns?

When a log burns, the process of combustion occurs, which involves a chemical reaction with oxygen. During this reaction, the organic compounds within the log, primarily cellulose, react with oxygen to produce water vapor and carbon dioxide as byproducts. This transformation indicates that the original matter in the log is not simply disappearing; rather, it is being converted into different substances due to the chemical reaction.

Additionally, while energy is released in the form of heat and light during this process, it is important to note that matter itself is conserved in the overall reaction. This aligns with the law of conservation of mass, where the total mass of reactants (the log and oxygen) equals the total mass of products (water vapor, carbon dioxide, and ash). Thus, although the original log turns into gases and residue, it is the change to water vapor and carbon dioxide that best captures what occurs to matter during the burning of wood.