Question

for each of the following activities, decide if it is an example of a physical or chemical change. provide justification for your choice:

1. a log burning on the fire

change:
justification:

1. boiling water

change:
justification:

1. frying an egg

change:
justification:

1. an iron pipe rusting

change:
justification:

1. an iceberg melting

change:
justification:

1. fruit rotting

change:
justification:

1. shredding cheese

change:
justification:

1. a pond freezing

change:
justification:

Explanation:

1. A log burning on the fire: Chemical change. Combustion creates new substances like carbon - dioxide and ash.
2. Boiling water: Physical change. Water changes state from liquid to gas without new substances.
3. Frying an egg: Chemical change. Heat causes proteins to denature and new substances form.
4. An iron pipe rusting: Chemical change. Iron reacts with oxygen to form iron oxide (rust).
5. An iceberg melting: Physical change. Ice changes from solid to liquid without new substances.
6. Fruit rotting: Chemical change. Microbial action causes chemical reactions and new substances.
7. Shredding cheese: Physical change. Only the shape and size change, no new substances.
8. A pond freezing: Physical change. Water changes from liquid to solid without new substances.

Answer:

1. Change: Chemical change

Justification: Combustion creates new substances.

1. Change: Physical change

Justification: State change without new substances.

1. Change: Chemical change

Justification: Protein denaturation forms new substances.

1. Change: Chemical change

Justification: Iron - oxygen reaction forms rust.

1. Change: Physical change

Justification: State change without new substances.

1. Change: Chemical change

Justification: Microbial action causes chemical reactions.

1. Change: Physical change

Justification: Shape and size change, no new substances.

1. Change: Physical change

Justification: State change without new substances.