Physical vs Chemical Change- Definition, 8 Major Differences, Examples

Physical Change Definition

A physical change is a process that changes the physical form of a substance but not its chemical composition.

  • During a physical change, the molecules of a substance are rearranged, but the chemical composition of the substance remains unchanged.
  • A physical change usually involves a change in physical properties like the change of strength, change of state, shape, size, color, etc.
  • Physical changes are reversible changes, but reversibility cannot be used as a criterion for classification as some changes can be irreversible.
  • Physical changes involving changes in the shape, size, and state of molecules involve the rearrangement of atoms.
  • Since the chemical composition of a substance is not changed as a result of physical change, no new substances are formed.
  • The amount of energy absorbed or released during a physical change is significantly less as the changes tend to be temporary.
  • Some examples of physical changes are melting of ice, breaking of glass, boiling water, etc.
Physical vs Chemical Change
Physical vs Chemical Change. Created with BioRender.com

Chemical Change Definition

A chemical change is a process that changes the chemical composition of a substance resulting in a new compound.

  • Chemical change involves either chemical synthesis or chemical decomposition. Chemical synthesis results in the formation of a new substance from two or more chemical substances. Chemical decomposition involves the breakdown of a chemical substance into two or more different substances.
  • Chemical changes are also called chemical reactions, most of which are irreversible, but some can be reversible.
  • During a chemical change, the atoms of the substance are rearranged, and the change is accompanied by a change in energy. Chemical reactions can either be endothermic or exothermic, depending on if they absorb or release energy.
  • Chemical changes can be categorized into three groups; inorganic changes, organic changes, and biochemical changes.
  • Inorganic changes are the reactions between elements and compounds, usually occurring in laboratories or in large-scale industries.
  • Organic chemical changes are reactions between organic compounds composed of carbon, hydrogen, and few other elements. 
  • Biochemical changes are the reactions occurring with living organisms during their growth and metabolism. Biochemical reactions are usually regulated by enzymes and hormones.
  • Some examples of chemical changes are burning paper, digestion, electroplating, etc.

8 Key differences (Physical vs Chemical Change)

Characteristics Physical Change Chemical Change
Definition A physical change is a process that changes the physical form of a substance but not its chemical composition. A chemical change is a process that changes the chemical composition of a substance resulting in a new compound.
Changes Physical changes involve the changes in the arrangement of atoms. Chemical changes involve changes in the chemical composition of the substance.
Energy Physical changes absorb or release a comparatively less amount of energy. Chemical changes are accompanied by the absorption or release of a significant amount of energy.
Original form The original form of the substance can be regained by simple means in most of the physical changes. The original form of the substance cannot be regained by simple physical means.
New substances No new substance can be formed as a result of physical changes. New substances can be formed as a result of chemical changes.
Reversibility Physical changes are usually reversible. Chemical changes are usually irreversible.
Composition The chemical composition of a matter remains unchanged after a physical change. The chemical composition of a matter changes after a chemical change.
Examples Some examples of physical changes are melting of ice, breaking of glass, boiling water, etc. Some examples of chemical changes are burning paper, digestion, electroplating, etc.

Examples of Physical Change

Melting of Ice

  • The melting of ice is an example of physical change as the shape and state of water change, but the chemical composition remains the same.
  • The conversion of ice into water and water into ice can be done easily by the process of melting and freezing, respectively.
  • It is a physical change as it is reversible and doesn’t change the chemical composition of the substance.
  • Water molecules in ice are closer than those in water; thus, changes occur in the position of the molecules but not their number.
  • The conversion of ice into water involves the absorption of energy in the form of heat energy.

Examples of Chemical Change

Digestion

  • Digestion is the process of conversion of large macromolecules into smaller molecules in the presence of specific enzymes.
  • It is a chemical change as the chemical composition of the substances changes as the larger molecule is broken down into smaller particles.
  • The change is a biochemical change that occurs in almost all living organisms throughout the world. In higher organisms, the process occurs within a system where a number of organs work together to complete the process.
  • In lower organisms, the process is less complex as these utilize comparatively less complex substances.

References and Sources

  • Gautum SD, Pant M and Adhikari NR (2016). Comprehensive Chemistry, Part 2. Sixth Edition. Heritage Publishers and Distributors Pvt. Ltd
  • https://byjus.com/chemistry/difference-between-physical-and-chemical-change/ 
  • https://sciencetrends.com/10-chemical-change-examples/ – 16%
  • https://en.m.wikipedia.org/wiki/Physical_change – 8%
  • https://www.thoughtco.com/definition-of-physical-change-605910 – 7%
  • https://tutors.com/lesson/chemical-change-definition-properties-examples – 3%
  • https://quizizz.com/admin/quiz/5d7024989f07ce001bd403a8/bio-unit-1-quiz – 1%
  • https://www.mysolutionguru.com/ps/physical-and-chemical-changes/252 – 1%
  • https://www.mariaregina.org/ourpages/auto/2016/6/9/48988952/Final_Review_tc_2_.pdf – 1%

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