Question

Which best describes why a chemical change is different than a physical changes?
A.
A chemical change is used to identify characteristics of a substance, and a physical change identifies the behavior of a substance when in a reaction.
B.
A chemical change results in a different state of matter, and a physical change results in a new substance being formed.
C.
A chemical change is used by scientists to create new substances, and a physical change happens naturally.
D.
A chemical change results in a new substan

Answer 1

Physical changes are reversible (reversal is often quite easy).*
Chemical changes are not reversible (reversal is often extremely difficult).*

Related Information:

Chemical change:

Bonds have changed; the substances present before the change, are different from those present after the change:

A substance reacts to form a new chemical entity

same atoms are used, but different molecules have been created.

Examples:

The electrolysis of water: the products are two different substances;

Combustion of hydrogen in oxygen; forms water and generates heat;

The body's combustion of glucose produces carbon dioxide and water;

Bread made into toast (partially oxidized bread) is not reversible;

Wood burned in a fireplace is not reversible;

Burning of the World Trade Center.

Physical Change:

State, size, shape, or color of a substance is changed basic character-unchanged; Change of physical properties, leaving basic character-unchanged.

Examples:


Melting of ice: change of state;

Bearing gold into a ring;

Grinding;

Cutting;

Folding;

Collapse of the World Trade Center


* Physical changes aren't always easy to reverse, and chemical changes aren't necessarily impossible to reverse.

Answer 2

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Answer 3

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Answer 4

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Answer 5

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