Ms. Pitt set up a classroom demonstration to show what happens when a sample of zinc metal is added to a flask containing hydrochloric acid (HCl). The diagram shows what the students in the classroom observed during the demonstration. The students made two other observations:
The flask felt warmer after adding the sample.
The sample became smaller over time.
a. Explain why the change to the balloon is evidence of a chemical reaction.
b. Explain why the flask feeling warmer after the sample was added is evidence of a chemical reaction.
The students learn that zinc metal does not dissolve in HCl.
c. Explain why the sample becoming smaller over time in HCl is evidence of a chemical reaction.