6. In the investigation shown in Fig. 15.10, steel wool was burned using a Bunsen burner flame.
Before Steel wool Plasticine
After
12 345 6 7 89 10
Foil to protect ruler :Fig. 15.10
Knife edge
a. Explain why the mass of the steel wool increases. b. Does this investigation obey the law of conservation of mass?
7. A student sets up the investigation shown in Fig. 15.11 to find out if the mass of a substance increases, decreases or stays the same when it goes from a solid to a liquid i.e. melts.
g :Fig. 15.11
a. Before the student started, they put some film over the top of the beaker. Why did they do this?
b. During the investigation, the student noticed some drops of water on the outside of the beaker. What caused these water droplets?
c. The student decided to dry the outside of the beaker before getting the final mass of the beaker after all the ice had melted. Was this the correct thing to do?
d. Did the mass of the overall set-up (the beaker, the film and the ice) increase, decrease or stay the same after the ice had melted? Explain your answer.