Final answer:
The mass of a burning sample of matter seems to decrease due to the conversion into ashes, but the Law of Conservation of Mass ensures the total mass remains unchanged as gases like carbon dioxide and water vapor are produced and released into the atmosphere.
Step-by-step explanation:
When a sample of matter such as wood burns, its mass appears to decrease as it is converted into ashes. However, the Law of Conservation of Mass states that matter cannot be created or destroyed, so the total mass remains constant. This means that the mass lost in the form of ashes is accounted for by the mass of the gases produced during combustion, such as carbon dioxide and water vapor, which float off into the atmosphere. So, if one were able to measure the mass of the wood before burning and the mass of all products after, including the gases released into the air, the total mass would be the same before and after the fire.
For example, if a 300 kg tree is burned, it may leave behind just 10 kg of ashes. The seeming disappearance of the other 290 kg is because it has been released as smoke into the atmosphere. The mass of the smoke combined with the mass of the ashes still equals the original 300 kg of the tree, fully demonstrating the conservation of mass in action.