Melting is a physical change. It is a process where a substance changes from a solid state to a liquid state due to an increase in temperature. 1 During melting, the chemical composition of the substance remains the same, only its physical state and arrangement of particles change.
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Key Takeaways: Is Melting a Physical or Chemical Change?
- Melting is a physical change because it involves a transition from a solid to a liquid state without any alteration in the chemical composition of the substance.
- During melting, the particles gain energy to overcome intermolecular forces, allowing them to move more freely.
- Melting is reversible, and the substance can solidify again through the removal of thermal energy.
Why is melting a physical change?
Melting is considered a physical change because it involves a change in the physical state of a substance without any alteration in its chemical composition or identity. 2 In other words, the substance undergoing melting retains its chemical properties before and after the process.
During melting, a solid substance is heated, and the thermal energy causes the individual particles (atoms, molecules, or ions) to gain enough kinetic energy to overcome the attractive forces holding them in a fixed arrangement. 3
As a result, the solid transitions into a liquid state, where the particles can move more freely while still maintaining their chemical identities.
The reverse process, solidification or freezing, occurs when a liquid substance loses enough thermal energy to allow the particles to reorganize into a regular structure, forming a solid again.
This change from liquid to solid is also a physical change because it involves a rearrangement of particles without any alteration in the chemical composition.
In summary, melting and solidification are physical changes because they involve only the interconversion between different physical states (solid, liquid) of a substance, without any modification of its chemical composition or properties.
Why is melting not a chemical change?
Melting is not a chemical change because it does not involve the breaking or forming of chemical bonds. It is solely a physical process where the substance transitions from a solid to a liquid state due to an increase in temperature.
In a chemical change, the substances involved undergo a transformation at the molecular level, resulting in the formation of new chemical compounds or the breaking down of existing ones. 4
This typically involves the breaking and forming of chemical bonds, leading to a change in the chemical composition and properties of the substance.
During melting, the particles within the substance gain enough energy to overcome the intermolecular forces holding them together in a solid lattice structure. As a result, they become more mobile and transition into a liquid state.
However, the individual molecules or atoms remain intact, and no new substances are formed.
To summarize, melting is classified as a physical change because it does not involve any alteration in the chemical composition or identity of the substance. It is solely a rearrangement of the particles within the substance as a response to increased temperature, without any chemical reactions taking place.
Further reading
Is Burning a Physical or Chemical Change?
Is Frying (or Cooking) an Egg a Chemical Change?
Is Cooking a Physical or Chemical Change?
Why is Digestion of Food a Chemical Change?
Is Milk Souring a Physical or Chemical Change?
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References
- Melting | Phase Change, Heat Transfer & Temperature. (n.d.). Encyclopedia Britannica. https://www.britannica.com/science/melting
- 3.3: Physical Change. (2020, July 16). Chemistry LibreTexts. https://chem.libretexts.org/Courses/Modesto_Junior_College/Chemistry_142%3A_Pre-General_Chemistry_(Brzezinski)/CHEM_142%3A_Text_(Brzezinski)/03%3A_Matter_and_Energy/3.03%3A_Physical_Change
- Simple Kinetic Theory. (2013, October 3). Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/States_of_Matter/Phase_Transitions/Simple_Kinetic_Theory
- 3.6: Changes in Matter – Physical and Chemical Changes. (2016, April 4). Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry/03%3A_Matter_and_Energy/3.06%3A_Changes_in_Matter_-_Physical_and_Chemical_Changes
