Some of the particles undergo a phase change and become a gas due to burning. An example would be CO2, which is lost in the air around/escapes into the atmosphere. Hope that helps!
Answer:The difference is found in the CO2 and water vapour, H2O, that escape to the atmosphere during combustion.
Explanation: Burning of logs is combustion reaction and the it can generally be represented by
CxHy + O2 === CO2 + H2O + Heat
This is a non reversible reaction because some of the constituents of the original log are being given off during combustion. Hence, the change in the mass.
