Question

Stephen and Josie are each heating a sample of the same unknown liquid during an experiment. They record their observations in the chart below.

Student Mass Before Heating (g) Mass After Heating (g)
Stephen 11.3 6.7
Josie 10.2 10.2

Both students heat their samples to the same temperature, but one student uses an open container, and the other uses a closed container. Using the law of conservation of mass, which statement best explains their differing results?
A.The law of conservation of mass was broken in Josie's experiment because Josie used an open container.
B.The law of conservation of mass was broken in Stephen's experiment because Stephen used a closed container.
C.The law of conservation of mass was not broken. Some of Stephen's sample escaped because he used an open container.
D.The law of conservation of mass was not broken. Josie's sample gained mass from the surrounding air because she used an open container.

Answer 1

D. The law of conservation of mass was not broken. Josie's sample gained mass from the surrounding air because she used an open container.