Shanice and Jalen are doing an experiment to investigate the law of conservation of mass. They heat a solid in an open container and record the mass of the solid before and after heating. The table shows their observations.

Question

 

Solid Mass (grams)
before heating 7.5
after heating 5.5

Which best describes the conservation of mass in this experiment?

A.
The law of conservation of mass was broken in this experiment because the mass of the solid decreased.

B.
The law of conservation of mass was not broken because the mass before heating was greater than the mass after heating.

C.
The law of conservation of mass was not broken because the solid was heated in an open container, allowing gases to escape.

D.
The law of conservation of mass was broken in this experiment because the solid was heated in an open container, allowing gases to escape.

Answer 1

The best answer is:

C. The law of conservation of mass was not broken because the solid was heated in an open container, allowing gases to escape.

In this experiment, the decrease in mass is likely due to the escape of gases (such as water vapor) when the solid is heated. Since matter can be lost to the environment in an open container, the total mass of the system (solid plus products of heating when measured collectively) may not account for the mass lost as gas, consistent with the law of conservation of mass when considering the entire system.