Reactions - Physical and Chemical Changes


Concept Definition

Study the primary definition of this concept, broken into general, basic, and advanced English definitions. Also see the mathematical definition and any requisite background information, such as conditions or previous definitions.

General Science

The substances are not altered chemically, but merely changed to another phase (i.e. gas, liquid, solid), separated, or combined.[1]


Real World Application

Discover processes or disciplines in the natural or man-made worlds that employ the concept.

Boiling water for a cup of noodles is a physical change that involves changing phase.

Tearing a piece of paper is a physical change that involves changing shape.

Pouring your liquid cake mix into different shapes using baking molds is a physical change with shape.

Making a snow man is a physical change for shape.

Turning a large chunk of iron into iron wire or nails is a physical change that may involve both phase change (melting the iron) and shape (molding or extruding the iron).



Learn important vocabulary for this concept, including words that might appear in assessments (tests, quizzes, homework, etc.) that indicate the use of this concept.

 Important Vocabulary

Term Context
  • Water boils at 100°C.
  • Water vapor condenses below 100°C.
  • Cutting a piece of paper is a physical change.
  • Water vapor deposits as frost on cold surfaces on winter mornings.
  • Sugar dissolves into water.
  • Acetone evaporates much more quickly than water at room temperature.
  • Pouring a suspension through a filter will separate the liquid from the solid particles.
  • Water freezes at 0°C.
  • Ice melts at 0°C.
  • Solid CO2, dry ice, sublimes into gaseous CO2.
  • Dirt pieces can be suspended in water to make mud.



Browse relevant videos from the Journal of Chemical Education's (JCE) Chemistry Comes Alive! library and other video sources.

Boiling Water

Boiling water is only a phase change. Therefore, it is a physical change.

Making a Snow Man

Making a snow man does not involve any chemical change. (Ok, maybe not the part where the snow man comes to life.) It only involves putting stuff together without reaction with each other.


Computer Animations

Experience computer simulators or animations that illustrate the concept discussed here. Many simulators or animations come with worksheets for use in class.


Classroom Demonstations

Investigate lab procedures suitable for live classroom demonstrations or guided student exploration.

Students requiring adaptations to gain the full benefit of a demonstration may find a worksheet with guided observations useful. Alternatively, a teacher may wish to use a worksheet with guided observations to model what observations all students should be making during a demonstration.

The Demonstration Observation Worksheet is available in

  • PDF [ready to print]
  • Word 2007/2008 DOCX [free to edit/adapt further]


Tear a piece of paper


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Tear a piece of paper

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Author: Claire Liu

Just tear a piece of paper to demonstrate that this action is a physical change.

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A piece of paper


tear it

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recyle the paper please

Difficulty:No specific experience required
Preparation Time:0.00 minutes Demonstration Time: 1 minutes
Availability of Materials:Not specified Cost of materials:
Last Updated:Fri 25 Feb 2011 15:38:06 EST Viewed:31653 times viewed

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Read a summary of the concept, indicating the enduring understanding students should retain after class.


There is a physical change if there is no new substance generated after the change. Ice and water are made of exactly the same the same substance, only the state is different. Physical changes also include energy exchanges or separation/combinations.


Works Cited

Review the works cited to write the researched parts of this page, such as the discover's biographical information and other areas.

 Works Cited

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