Why is the tearing of paper a physical change not a chemical change?
Observing members:
0
Composing members:
0
7 Answers
The chemical bonds in the paper molecules (cellulose) are not being broken, and no new materials are being formed as a by-product. Chemical change implies a change in the chemical make-up of the reagents. I.e., the breaking of some bonds and formation of other bonds. Alternatively, ionization and radical formation could be thought of as chemical change. Phase change would be a change between solid, liquid, or vapor. Tearing does not classify as any of these.
Said another way, paper is lots of cellulose fibers that have been mashed into a thin film and then allowed to dry. When you tear the paper, it is just tearing this film. The fibers themselves are not destroyed. You could take torn paper, get it warm and wet, and then make new paper from it. This is because the cellulose fibers are intact.
Another example: human beings cannot digest cellulose (e.g., grass). It passes through our digestive system as fiber. Other animals can digest cellulose (cattle, rabbits) because they have special mechanisms (multiple stomachs, intestinal bacteria) for chemically breaking the cellulose structure down into simple sugars. Simply tearing the grass into very small bits does not release the energy stored in the cellulose. To metabolize cellulose one must actually break the chemical bonds that form it.
Does this help?
I love it when people come here for homework. :-P
Answer this question 
This question is in the General Section. Responses must be helpful and on-topic.
Composing members:
0
