Introduction
There are two types of changes in nature. These are:
- Physical change
- Chemical change
Physical change is a change in which the substance changes form but keeps its same chemical composition (reversible). In other words, Physical Change is one that is temporary and can easily be reversed. In this case, no new substance is formed.
Changes of state are considered to be physical changes. Liquid water and ice (frozen water) are both the same substance, water.
If you fold a piece of paper it is a physical change. You have changed the form of the paper but you have not changed the fact that it is paper.
If you heat an iron bar until it glows red hot, it is still chemically the same iron. The iron has not changed into something else.
If you dissolve salt in water you have not changed the materials chemically. You still have salt and you still have water. This can be shown if you choose to separate the mixture by distillation or the simple evaporation of the water. The salt would be the residue and the water would be the distillate.
Examples of physical changes include:
- Dissolution of sugar in water
- Freezing of liquid to solid
- Liquefaction of gases to liquid
- Melting of solid to liquids
- Sublimation
- Evaporation
- Crystallization
- Distillation and fractional distillation
- Heating of iron, ring boiler, cooker…
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https://passnownow.com/lesson/physical-and-chemical-change/
