Answer:
The Law of Conservation of Matter states that in a chemical reaction, matter is not created or destroyed. However, it is possible for the mass of a substance to change during a chemical reaction, as you observed.
When a substance burns, it reacts with oxygen in the air to form new compounds. For example, when wood burns, it reacts with oxygen to form water and carbon dioxide. The mass of the wood plus the mass of the oxygen is equal to the mass of the water and carbon dioxide produced.
In this case, the extra mass that you observed came from the oxygen that reacted with the wood. Oxygen has mass, and when it reacts with the wood, the mass of the resulting compounds is greater than the mass of the starting materials.
It's important to note that energy is not a form of matter, and therefore has no mass. However, energy can be converted into matter and vice versa, according to the famous equation E=mc^2, where E is energy, m is mass, and c is the speed of light. This equation demonstrates that mass and energy are fundamentally connected and can be converted into each other under certain conditions.
Step-by-step explanation: