Laura put an underwater plant in a glass jar full of water and sealed the lid to create a closed system. She recorded the mass of the jar with the plant inside it as 538 grams. She put the jar on a sunny windowsill and observed that the plant showed noticeable growth after several days. After a week, she again recorded the mass.

Question

Which statement is a reasonable prediction about what Laura should observe?

Responses

No prediction can be made because there is not sufficient information provided.

No prediction can be made because there is not sufficient information provided.

The new mass is 521 g because the plant consumed carbon dioxide, removing it from the system.

The new mass is 521 g because the plant consumed carbon dioxide, removing it from the system.

The new mass is 538 g because the atoms in the system did not change as the plant consumed carbon dioxide and produced oxygen.

The new mass is 538 g because the atoms in the system did not change as the plant consumed carbon dioxide and produced oxygen.

The new mass is 551 g because the growing plant produced oxygen, adding it to the system.

Answer 1

The best and most reasonable prediction about what Laura should observe after a week is:

The new mass is 538 g because the atoms in the system did not change as the plant consumed carbon dioxide and produced oxygen.

In a closed system, the total mass remains constant because matter cannot enter or leave the system. Although the plant is undergoing photosynthesis, converting carbon dioxide and water into glucose and oxygen, the overall mass of the closed system remains unchanged because the mass of the reactants (carbon dioxide and water) is equal to the mass of the products (glucose and oxygen) plus the mass of the plant itself.