1. A piece of paper inside a sealed steel container is ignited and allowed to burn. Which of the following best predicts what will happen to the mass of the sealed container and its contents after the paper burns?
Answer: A
The mass will not change, because atoms will be neither created nor destroyed inside the sealed container.
The mass of the sealed container and its contents will remain constant after the paper burns, as the law of conservation of mass states that mass cannot be created or destroyed in a closed system.
A) The mass will not change, because atoms will be neither created nor destroyed inside the sealed container.
This option is correct because it accurately reflects the principle of conservation of mass. In a sealed environment, all the reactants (paper and oxygen) and products (gas and ash) are accounted for, meaning the total mass remains unchanged despite the chemical reactions occurring.
B) The mass will decrease, because the burning process will convert some of the solid paper into a gas.
This option is incorrect. While it is true that some of the paper is converted into gas, the mass of the gases produced is still contained within the sealed container. Thus, the total mass remains the same, as it includes all products of the reaction.
C) The mass will increase, because the paper will combine with oxygen inside the sealed container and produce ash.
This option is also incorrect. Although the paper combines with oxygen during combustion, it does not lead to an increase in mass. The mass of the ash and gases produced from the burning paper, when measured together with the remaining contents of the container, will equal the original mass.
D) The mass could either increase or decrease, depending on how much of the paper burns and how much heat is produced.
This option is misleading. The mass cannot increase or decrease in a sealed system regardless of the amount of paper that burns. Heat production does not affect the overall mass in this context, and all matter remains within the container.
Conclusion
The correct answer, A, is definitive because it aligns with the law of conservation of mass, stating that mass in a closed system remains constant. Options B, C, and D fail to recognize that all mass, including gaseous products, is contained within the sealed container, thus not allowing for any net change in mass.