Question

When an object is burning, two atoms of oxygen (in the air) combine with one atom of carbon (from the

substance burning). This forms carbon dioxide gas. Explain how the law of conservation of matter applies to

this reaction.

2. A piece of wood is burned, and a small amount of ashes are formed. Explain why the original piece of wood

and the resulting ashes will not weigh the same.

Answer 1

1. The law of conservation of mass applies to this reaction because when you look at its balanced chemical equation, the same amount or ratio of elements can be found:

C + O2 --> CO2

This shows that the product will have the same ratio of reactants.

2. The original piece of wood and resulting ashes do not weight the same because the combustible parts of the wood were burned and converted to gases. This means that the missing mass is equal to the gases produced. The remaining ashes are the incombustible parts of the wood.