Question

what is a physical change and chemical change ? give 2 examples of both changes

Answer 1

rowseNotessearch

Search for any book or any question

HOMEWORK HELP > SCIENCE
Are there more examples of changes that are both chemical and physical other than a candle burning?
print Print document PDF list Cite
Expert Answers
T-NEZ eNotes educator| CERTIFIED EDUCATOR

A change can't be both physical and chemical, but physical and chemical changes can occur simultaneously. This is what's happening with the burning candle: the wax is melting, which is a physical change, and it's combusting, which is a chemical change. A physical change is a change in state, such as melting, freezing, evaporation or condensation, or a change in form, such as grinding a substance into a powder. There's no change in the chemical formula of the substance. A chemical change is one in which a new substance is formed.

The cycle of an internal combustion engine involves both a physical and chemical change. Gasoline is vaporized and the air in the cylinders is compressed, a physical change, before being ignited and combusting, a chemical change.

Digestion is another example of both. Food is physically broken down by chewing and chemically broken down by digestive enzymes in the saliva and acid in the stomach.

A third example is weathering in nature. Rocks are physically changed by wind, running water, expansion of ice as it freezes, abrasive wind and water-borne sediments. They are chemically changed by oxygen, acid rain and acidic compounds produced by decomposers.

Answer 2

$\large{\sf{\red{\underline{\underline{Hello \:GM}}}}}$

Properties such as shape, size, colour and state of a substance are called it's physical properties. A change in which a substance undergoes a change a physical properties is called a physical change. A physical change is generally reversible. In a such change no new substance is formed..