Physical changes are modifications or transformations that occur in any substance but do not involve a change in its nature or composition. The latter would imply a chemical change .
Physical changes occur in relation to volume, shape, or even state. Therefore, they can be detected through observation or measurement of the body in question.
A very simple way to recognize if some matter has undergone a physical change is that it can be reversed and returned to its previous state.
See also: Physical phenomena
Types of physical changes
Within the physical changes we can identify three large groups:
Volume changes
- Expansion. This is the change that occurs when, after a body comes into contact with certain elevated temperatures, its size increases. Expansion can affect substances in solid, liquid, and gaseous states .
- Shrinkage. In contrast to the previous change, this one reduces the element’s size after coming into contact with low temperatures.
Regressive changes
Changes like these occur when bodies cool. Three types of these changes can be identified:
- Condensation. When we talk about this change, we are referring to the transformation of a body from a solid state to one in a liquid state.
- Solidification. As its name suggests, in this case the body becomes solid, having previously been a liquid.
- Regressive sublimation. This change occurs when an element goes from a gaseous state to a solid.
Regressive changes
Changes like these occur when bodies come into contact with high temperatures . Four types of these changes can be identified, as detailed below:
- Evaporation. In this case, the substance changes from a liquid to a gaseous state as a result of high temperatures. This phenomenon can also occur at room temperature.
- Boiling. While in the previous case only the surface particles are affected, in this case, all particles are affected. It also involves the transition from a liquid to a solid state.
- Fusion. This change is observed when a substance goes from a solid to a liquid state after being heated to high temperatures.
- Progressive sublimation. In this case, after the substance comes into contact with high temperatures, it changes from a solid to a gaseous state.
See also: Temporary and permanent transformations
Examples of physical changes
Below is a list of physical changes as an example:
- When an ice cube is placed near a fire and it melts, it goes from a solid to a liquid state, but without losing its nature.
- When a sheet of paper is torn into several pieces.
- When the mercury in a thermometer comes into contact with high temperatures, its size expands, but this does not change its nature.
- When water is boiled in a pot, it changes from a solid to a gaseous state.
- When a window fogs up, droplets begin to form after a while. This is a consequence of the water vapor transforming into liquid.
- When ice cream is left out of the freezer and thaws.
- When glass comes into contact with high temperatures, it becomes more malleable.
- When a piece of cheese is grated with a grater.
- When clouds collide and it rains, the water changes from a gaseous state to a liquid state.
- When a metal such as gold is melted, it goes from a solid to a liquid state.
- Dissolve a tablespoon of sugar in a glass of water. Although it dissolves, neither element can change its properties.
- When we forget a bottle of Coca-Cola in the freezer and it freezes, it goes from a liquid to a solid state.
- When temperatures rise, the cement on the road swells and sometimes even cracks.
- When a piece of iron is filed.
- When we leave a bottle of alcohol open and it evaporates.
- When we fill coolers with water and put them in the freezer, we’ll soon have ice cubes. In this case, the water changes from a liquid to a solid state.
- When we wash our hair and then dry it with a hairdryer.
- When we break a stone into several pieces.
- When we mold a piece of plasticine.
- Over time, perfumes evaporate. That is, they change from a liquid to a gaseous state.
