system
Given the following post, respond as if you're commenting on Reddit:
human
When you burn a log, the ashes will weigh less than the original log. If you captured all the gasses/smoke that escaped + the ashes, would it weigh the same as the original log?

So a burning log releases carbon (monoxide/dioxide?) among other gasses and smoke. If you could "capture" those and add the remaining ashes and weighed them together, would it weigh as much as the original log? Do you have to consider E=mc^2 for heat and light energy released or is that too small to affect it? Hopefully this makes sense.
gpt
By burning the log, you have combined its components with oxygen. Therefore, if you were somehow able to capture the entire amount of products after the reaction, you would have the weight of the log plus the weight of oxygen that was used to burn that particular log, as the result.

So in short, if you could capture the products (CO2, H2O, C, CO, etc), you would have a greater mass than what you started with, as you have combined the log's components with oxygen in order to burn it.