When paper burns, the mass of the ash that remains is less than the mass of the paper.

Question

Does this situation violate conservation of mass?

Responses

Yes, because the ashes have less mass than the paper.
Yes, because the ashes have less mass than the paper.

No, because the dry ashes, if mixed with water, can be used to remake the paper.
No, because the dry ashes, if mixed with water, can be used to remake the paper.

No, because the mass of gases that form during burning must also be considered.
No, because the mass of gases that form during burning must also be considered.

Yes, because conservation of mass does not apply to burning reactions.

Answer 1

The correct response is:

No, because the mass of gases that form during burning must also be considered.

When paper burns, it undergoes a chemical reaction that converts it into ash, gases (such as carbon dioxide and water vapor), and heat. The mass of the ash that remains is less than the original mass of the paper because the mass of the gases released into the atmosphere during combustion is not accounted for in the remaining solid ash. Conservation of mass holds true, as the total mass of the reactants (paper) will equal the total mass of the products (ash and gases) when considering all substances involved in the reaction.