Question

3.12 what type of change, physical or chemical, takes place in each of the following?
a. pie dough is rolled into thin pieces for a crust.
b. a silver pin tarnishes in the air.
c. a tree is cut into boards at a saw mill.
d. food is digested.
e. a chocolate bar melts.

Explanation:

• a. Rolling pie - dough changes its shape but not its chemical composition, so it's a physical change.
• b. Tarnishing of silver is due to a chemical reaction between silver and substances in the air, so it's a chemical change.
• c. Cutting a tree into boards only changes its physical form, not its chemical nature, so it's a physical change.
• d. Digestion of food involves chemical reactions to break down complex substances into simpler ones, so it's a chemical change.
• e. Melting a chocolate bar changes its state from solid to liquid without altering its chemical makeup, so it's a physical change.

Answer:

a. Physical change
b. Chemical change
c. Physical change
d. Chemical change
e. Physical change