Question

During an experiment, you weigh the mass of a piece of wood as 200 grams.

You burn it so that the smoke released can turn a small turbine above the
burning wood. Afterwards, you weigh the mass of the ashes as 90 grams.
Why has your experiment not broken the Law of Conservation of Mass?
A. The Law of Conservation of Mass does not apply to combustion reactions.
B. The missing mass was released in the smoke, which was not weighed, making it seem
like there is less mass in the products than the reactants.
C. All of the missing mass has been converted into heat energy. It doesn't affect the Law of
Conservation of Mass because it uses Einstein's law E = MC2 instead.
D. Some of the total energy of the reaction was used to turn the turbine, so there should be
less mass overall in the products of the reaction.
Reset Selection

Answer 1

Answer is B.

According to the Law of Conservation of Mass, mass can not be destroyed nor created under normal circumstances. When you first weigh the wood, it is the exact mass because nothing was changed to it, no burning, no splitting, no nothing. After the wood was burned part of the mass was sent off as smoke and and in the form of a gas. Burning is natural, and is not an unnatural circumstance. Therefore, the Law still applies in this scenario.